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Sexual behaviour and smoking as determinants of cervical HPV infection and of CIN3 among those infected: a case–control study nested within the Manchester cohort

Sexual behaviour and smoking as determinants of cervical HPV infection and of CIN3 among those... British Journal of Cancer(2000) 88(11), 1565–1572 © 2000 Cancer Research Campaign doi: 10.1054/ bjoc.2000.1523, available online at http://www.idealibrary.com on http://www.bjcancer.com Sexual behaviour and smoking as determinants of cervical HPV infection and of CIN3 among those infected: a case–control study nested within the Manchester cohort 1 1 2 2 1 1 1 JM Deacon, CD Evans, R Yule, M Desai, W Binns, C Taylorand J Peto 1 2 Section of Epidemiology, Institute of Cancer Research, 15 Cotswold Road, Belmont, Sutton, Surrey, SM2 5NG; Department of Cytology, Christie Hospital NHS Trust, Wilmslow Road, Withington, Manchester, M20 4BX, UK Summary To distinguish risk factors for acquisition of cervical human papillomavirus (HPV) infection from the determinants of n eoplasia among infected individuals we have conducted a three-arm case-control study nested within a large population-based cohort of women (the Manchester cohort) screened for HPV at entry using L1 consensus primer PCR. The study includes 181 HPV-positive controls who did not develop high-grade cervical intraepithelial neoplasia (CIN3) during follow-up, 203 HPV-negative controls, and 199 HPV-positive cases with histologically confirmed CIN3. Detailed information on sexual, reproductive and gynaecological history, oral contraceptive use and smoking was obtained at face-to-face interview. There was a striking division between risk factors for infection and those predictive of disease. Comparing the HPV-positive against the HPV-negative controls, the only risk factors for infection were number of sexual partner s (OR for six or more = 3.89; 95% Cl = 1.99–7.62), a relatively recent new sexual relationship (OR for a new partner within the previous 2 years = 4.17; 95% Cl = 2.13–8.33), and a history of previous miscarriage (OR = 2.59; 95% Cl = 1.28–5.21). The determinants of CIN3 among infe cted women were, in contrast, early age at first intercourse (OR for 16 years old or less = 3.23; 95% Cl = 1.33–7.69), a long time since starting a new sexual relationship (OR for 6 years or more = 4.94; 95% Cl = 2.51–9.71), and cigarette smoking, with strong evidence for a dose– response (OR for current smoking habit 20+ per day = 2.57; 95% Cl = 1.49–4.45). Oral contraceptive use was not significantly associated with either HPV infection or CIN3. © 2000 Cancer Research Campaign http://www.bjcancer.com Keywords: cervical neoplasia; CIN3; HPV; sexual behaviour; smoking Human papillomavirus (HPV) infection has now been accepted as we have conducted a three-arm interview-based case-control study the primary cause of cervical neoplasia (Schiffman, 1992; Bosch in which the basis for case and control selection was HPV infec- et al, 1995; IARC, 1995; Walboomers et al, 1999). Oncogenic tion as well as disease status. The study was nested in a large popu- genital HPVs, however, are highly prevalent in many populations lation-based cohort undergoing routine cervical screening in the where CIN3 and cervical cancer remain relatively rare (Bauer city of Manchester, where cervical cell samples for HPV analysis et al, 1991, 1993; Hildesheim et al, 1993; Melkert et al, 1993; had been collected from all participants at entry (Peto et al, in Wheeler et al, 1993) and natural history studies have shown that preparation). It includes 199 cases of histologically confirmed most infections are transient and not associated with detectable CIN3 diagnosed after entry to the cohort in women known to be cytological abnormality (Evander et al, 1995; Hinchliffe et al, HPV-positive, 181 women infected with HPV but without CIN3 1995; Ho et al, 1998). The reasons for this variable natural history and 203 HPV-negative controls. are poorly understood but it has been generally assumed that other causes or co-factors must be important for the development of neoplasia in HPV-infected individuals. In addition to sexual MATERIALS AND METHODS activity, case-control studies have identified a number of other possible factors including high parity, the presence of other chronic The cohort genital infections, cigarette smoking and oral contraceptive use The recruitment of the Manchester cohort and the methods of data (Brinton, 1992). These effects may, however, be due at least partly collection and follow-up are described elsewhere (Peto et al, in to the correlation between sexual behaviour and other risk factors, preparation). Briefly, between 1987 and 1993, in collaboration and the failure in most studies to control adequately for con- with over 100 general practitioners and screening clinics in the founding by HPV (Layde, 1989; Phillips and Davey Smith, Greater Manchester area who used the Christie Hospital cytology 1994). service, we collected 78 062 cervical cell samples from 61 570 In an attempt to resolve these problems, and to distinguish women attending for routine screening. The cell samples were between risk factors for the acquisition of cervical HPV infection obtained by elution from spatulas used to take Pap smears. There and co-factors for the development of CIN3 among those infected, was no age restriction for participants. All samples were allocated a unique identifying number (ID) and were stored in buffer Received 8 June 2000 at –40˚C. Through regular data linkage of the study IDs with the Revised 31 August 2000 main laboratory database, the screening records of cohort mem- Accepted 31 August 2000 bers and the histology results of any cervical biopsies have been Correspondence to: JM Deacon updated. 1565 1566 JM Deacon et al Case-control study – eligibility criteria generic probe but negative to all type-specific probes were desig- nated as positive, but untyped. This study was restricted to white women of any age who had been routinely and satisfactorily screened at least once through Interviews the Christie laboratory prior to entry to the main cohort, and who had had a smear and concurrent spatula cell sample (termed The ID numbers of potentially eligible cases and controls with ‘spatula’) taken on or after 1 July 1988, that were diagnostically adequate HPV results were identified to the Christie Hospital, adequate both for cytology and for PCR. These samples were the where eligibility was checked as far as was possible from routine ‘index’ smear and spatula that defined a woman’s age and HPV records. A senior clinician (RY) then contacted the general practi- status. Women were excluded if they had had a hysterectomy, a tioner of each woman to obtain approval for an interviewer to previous malignancy or previous CIN3, if they suffered from contact the patient and invite her to participate. Between August serious psychiatric illness, or if they were known to have moved 1990 and July 1996 interviews were conducted in the women’s out of the study area since entry to the cohort. Because of the homes by one of two trained interviewers using a structured temporary nature of their residence in the city, students at questionnaire. Information collected included demographic data, Manchester’s several universities and colleges of further educa- menstrual, reproductive and gynaecological history, sexual history tion were also excluded. The cytological result of the index and information on smoking habits. Sexual, contraceptive and smear was not a criterion for determining either case or control reproductive histories were collected on a calendar with a record eligibility. for every month of a woman’s life from the age of menarche (or first intercourse, whichever was earlier) up to the date of index Case identification smear. Inconsistent data were rechecked with study participants by telephone. The data were then anonymized, coded and entered on Cases were all those women in the cohort, eligible by the above computer. criteria, who developed histologically diagnosed CIN3 within 3 years of their index smear. Statistical analysis Control selection All risk factor analyses relate to exposures prior to the index spatula date. Two separate analyses were performed. The first, Two control groups of approximately equal size were identified, analysing risk factors for the acquisition of HPV infection, the first consisting of women found, on PCR screening of their compared HPV-positive controls with HPV-negative controls. The index spatulas, to be HPV-positive, and the second consisting of second, analysing risk factors for the development of CIN3 among HPV-negative women. No control had CIN3 diagnosed at any time those infected with HPV, compared the CIN3 cases with the HPV- during her follow-up but women with CIN1 or 2 were not positive controls. The age stratification of the study design was excluded. Potential controls were identified through stratified maintained in univariate and multivariate conditional logistic random sampling. All the spatulas collected since 1 July 1988 regression analyses (Breslow and Day, 1980) using the STATA for from eligible women in the cohort were stratified by date (1-year Windows® program package. Relative risks were estimated as periods: 1 July 1988 to 30 June 1989, etc) and age of the woman at odds ratios (OR) with approximate 95% confidence intervals. χ the time (5-year age groups: < 20, 20–24, 25–29, etc). Within each values for differences are Mantel–Haenszel corrected. Tests for age/period stratum spatulas were submitted for HPV testing in linear trend of log odds were performed by scoring categories of random order. Testing continued until the number of HPV-positive exposure and fitting them as continuous variables. All P values are spatulas identified roughly equalled the number of cases in each two-sided. stratum. In instances where a woman had two or more spatulas independently selected for random testing, the earlier was defined as her index. Controls approached for interview were the first RESULTS HPV-positive and HPV-negative women in their stratum to be identified by the random HPV testing. 315 potential cases and 583 potential controls were identified by the HPV laboratory and determined from the cytology database and GP records to be eligible. Of these, 232 cases (74%) and 384 HPV detection and genotyping controls (181 HPV-positive and 203 HPV-negative, total 66%) HPV DNA in the index spatulas of cases and the random potential Table 1 Age distributions of interviewed women by case/control status controls was assayed at the Institute of Cancer Research using L1 Age HPV+ve CIN3 Cases HPV+ve Controls HPV–veControls consensus PCR amplification with the MY09/MY11 primer pair as (n) (%) (n) (%) (n) (%) described in detail elsewhere (Bauer et al, 1992; Manos et al, 1989). Concurrent amplification of a 286 bp human β-globin frag- < 20 4 (2.0) 7 (3.8) 5 (2.5) ment was used as an internal control, its failure to amplify desig- 20–24 19 (9.6) 19 (10.5) 21 (10.3) nating a sample inadequate. Consensus HPV-product was detected 25–29 52 (26.1) 47 (26.0) 49 (24.1) using a biotinylated generic probe and enhanced chemilumines- 30–34 49 (24.6) 40 (22.1) 47 (23.2) 35–39 32 (16.1) 29 (16.0) 32 (15.8) cence (Amersham International). Positive samples were hybrid- 40–44 23 (11.6) 19 (10.5) 21 (10.3) ized with type-specific oligonucleotide probes to determine the 45–49 7 (3.5) 9 (5.0) 12 (5.9) virus genotypes present (types 6/11/42 (mixed), 16, 18, 26, 31, 33, 50+ 13 (6.5) 11 (6.1) 16 (7.9) 35, 39, 40, 45, 51, 52, 53, 54, 55, 56, 57, 58, 59, 73, ME180, PAP88 Total 199 181 203 (HPV66), PAP155, PAP291 and W13B). Samples positive to the British Journal of Cancer (2000) 83(11), 1565–1572 © 2000 Cancer Research Campaign Manchester case–control study of CIN31567 Table 2 Characteristics of cases and controls: univariate odds ratios for HPV infection among controls, and CIN3 among those infected HPV+ve Controls vs HPV ve Controls HPV+ve Cases vs HPV+ve Controls +ve –ve OR 95% Cl Ca Con OR 95%CI Marital status Married 83 130 1.00 92 83 1.00 Cohabiting 26 19 2.02 (1.03–3.98) 35 26 1.22 (0.67–2.24) Wid/Sep/Div 35 20 2.59 (1.40–4.79) 36 35 0.83 (0.47–1.47) Single 37 34 1.61 (0.88–2.94) 36 37 0.95 (0.52–1.71) Age left full-time education 13–15 44 52 1.00 68 44 1.00 16–18 104 121 0.88 (0.52–1.52) 110 104 0.66 (0.39–1.12) 19–21 19 18 1.10 (0.50–2.43) 13 19 0.40 (0.17–0.93) 22+ 14 12 1.24 (0.51–3.02) 8 14 0.34 (0.13–0.90) Age at menarche ≤11 24 45 1.00 37 24 1.00 12 27 28 1.68 (0.81–3.51) 42 27 1.03 (0.51–2.09) 13 57 56 1.85 (1.00–3.45) 50 57 0.55 (0.27–1.04) 14 45 43 1.90 (0.99–3.62) 39 45 0.53 (0.27–1.04) 15+ 28 31 1.61 (0.79–3.28) 31 28 0.71 (0.34–1.47) Number of full-term pregnancies 0 71 64 1.00 63 71 1.00 1 33 37 0.79 (0.44–1.42) 46 33 1.57 (0.88–2.77) 2 51 68 0.68 (0.40–1.17) 49 51 1.13 (0.64–1.99) 3+ 26 34 0.69 (0.35–1.38) 41 26 1.90 (0.94–3.85) Age at first birth 15–19 28 35 1.00 41 28 1.00 20+ 82 104 0.93 (0.51–1.71) 95 82 0.74 (0.41–1.33) Ever had a spontaneous abortion No 152 185 1.00 169 152 1.00 Yes 29 18 2.24 (1.17–4.30) 30 29 0.95 (0.54–1.68) Ever had an induced abortion No 154 189 1.00 176 154 1.00 Yes 27 14 2.35 (1.18–4.67) 23 27 0.75 (0.41–1.36) Age at first intercourse ≤16 52 58 1.00 87 52 1.00 17–20 104 113 1.08 (0.67–1.74) 98 104 0.51 (0.32–0.80) 21+ 25 32 0.90 (0.45–1.84) 14 25 0.25 (0.11–0.57) Total number of sexual partners 1 39 83 1.00 39 39 1.00 2–5 100 93 2.28 (1.40–3.70) 121 100 1.24 (0.72–2.12) 6+ 40 25 3.52 (1.84–6.76) 39 40 0.96 (0.50–1.84) Number of regular partners 1 47 93 1.00 46 47 1.00 2 50 57 1.79 (1.06–3.04) 82 50 1.66 (0.96–2.88) 3 49 26 3.82 (2.07–7.05) 39 49 0.82 (0.45–1.51) 4+ 34 26 2.65 (1.41–4.99) 32 34 0.91 (0.48–1.75) Years since start of latest regular relationship <2 50 21 1.00 24 50 1.00 2–5 56 37 0.72 (0.37–1.39) 48 56 1.65 (0.87–3.13) h h 6+ 74 144 0.19 (0.10–0.35) 127 74 4.06 (2.21–7.44) Ever had a sexually transmitted disease No 100 108 1.00 102 100 1.00 Yes 81 95 0.91 (0.61–1.37) 97 81 1.16 (0.77–1.74) Ever had a partner with genital warts No 170 199 1.00 187 170 1.00 Yes 11 4 3.01 (0.95–9.60) 12 11 1.04 (0.44–2.42) Months using barrier contraception 0 101 95 1.00 110 101 1.00 1–12 28 26 1.00 (0.55–1.84) 29 28 0.91 (0.50–1.64) 13–48 24 38 0.59 (0.33–1.06) 32 24 1.20 (0.66–2.19) 49+ 28 44 0.64 (0.36–1.14) 28 28 0.93 (0.51–1.70) Oral contraceptive use Never 35 38 1.00 32 35 1.00 Ex-user 96 116 0.78 (0.43–1.43) 108 96 1.15 (0.63–2.10) Current user 50 49 0.95 (0.48–1.89) 59 50 1.28 (0.66–2.50) Ever smoked No 92 98 1.00 65 92 1.00 Yes 89 105 0.90 (0.60–1.35) 134 89 2.20 (1.44–3.35) a b c d e f g h Stratified by 5-year age group; P < 0.05; P < 0.005; P < 0.0005; P for trend < 0.01; P for trend < 0.001; P for trend < 0.0005; P for trend < 0.0001 © 2000 Cancer Research Campaign British Journal of Cancer (2000) 83(11), 1565–1572 1568 JM Deacon et al were successfully interviewed. Among the interviewed cases there diagnosed as the direct result of an abnormal smear, and as this were 33 (14%) whose index spatula tested HPV-negative with the study was conducted early in the history of the cohort it was the L1 consensus primer system in spite of multiple attempts at ampli- index smear that was abnormal in each case, 91 (46%) showing fication under different conditions. These women did not differ severe dyskaryosis and 108 (54%) showing lower grades of from the HPV-positive cases with regard to age, cytology results, abnormality from atypia to moderate dyskaryosis. Among the social class, sexual, obstetric or contraceptive history. They were HPV-positive controls 22 (12%) had an index smear showing a 50% more likely than HPV-positive cases to have smoked but this transient mild abnormality that resolved within a year. A further 22 difference was not significant (χ = 0.63, P = 0.43). PCR using had persistent dyskaryosis and of these 11 had mild or moderate (1df) different primers has not yet been attempted with these samples dysplasia found at biopsy. Cytological abnormality was rare in and it is not clear whether they represent truly HPV-unrelated uninfected women, seven (3.5%) having transient dyskaryosis and CIN3 or if they are false-negatives. Because of this uncertainty one having reportedly persistent severe dyskaryosis that showed these cases have been excluded from the current analyses. The CIN1 on biopsy. data presented thus relate to 199 HPV-positive cases of CIN3, 181 Table 2 shows the distributions of cases and controls according HPV-positive controls and 203 HPV-negative controls. to selected characteristics and risk factors. Odds ratios are strati- The refusal rate was low and similar in cases and controls (15% fied by age according to the 5-year strata used for sampling, but and 13% respectively) and was unrelated to age. The main reason are otherwise unadjusted. In none of the analyses was there any for failure to interview was inability to trace the woman (18% evidence of heterogeneity of risk according to age. Among the overall). Untraced women were those whose medical records and controls risk of HPV infection was very strongly related to sexual health authority registers recorded them as being still resident, but behaviour. Both a woman’s total lifetime number of sexual part- whom the interviewers found not to be at their registered address. ners and her number of regular (longer than 3 months) relation- Among both cases and controls untraced women were signific- ships were highly predictive of risk (P for trend < 0.001). antly younger than those interviewed, reflecting the high mobility HPV-infected women were also much more likely than uninfected of a fit young urban population; χ for the difference between controls to have commenced a new regular relationship within the (1df) women under 30 and over 30 years was 8.67 (P < 0.005) for the past year. There was a moderately significant association between cases and 15.13 (P < 0.0005) for controls. Significantly more infection and history of miscarriage that was consistent in all controls (20%) than cases (11%) remained untraced at the end of analyses, remaining essentially unchanged after multivariate the study (χ for the difference = 12.81, P < 0.0005), probably regression (see Table 5). No other risk factors for HPV infection (1df) because the cases were under continuing medical surveillance and were identified. The associations between marital status, thera- hence their records were more accurate. Four controls (2 HPV peutic abortion and HPV infection disappeared after adjustment infected, 2 uninfected) who did not answer all the sexual questions for number of partners and recency of the latest relationship. There and one HPV negative control who reported no regular partners was no association in this data set between cervical HPV infection were excluded from multivariate analyses involving these and history of other sexually transmitted diseases (trichomonas, variables (see Table 5). genital warts, genital herpes or gonorrhoea), use of barrier Table 1 shows the age distributions of cases and controls. These contraception, oral contraceptives (OCs) or smoking. have been balanced by the stratified sampling process and reflect In the comparison of HPV-positive CIN3 cases against HPV- the age distribution of participating CIN3 cases. All the cases were positive controls the only important determinants of disease were Table 3 Univariate odds ratios for different smoking variables HPV+ve Controls vs HPV–ve Controls HPV+ve Cases vs HPV+ve Controls +ve –ve OR 95% Cl Ca Con OR 95%Cl Ever smoked No 92 98 1.00 65 92 1.00 Yes 89 105 0.90 (0.60–1.35) 134 89 2.20 (1.44–3.35) Current daily smoking habit (cigarettes/day) Never 92 98 1.00 65 92 1.00 Ex 15 27 0.66 (0.32–1.35) 22 15 2.14 (1.03–4.45) 1–19 35 45 0.79 (0.46–1.34) 38 35 1.58 (0.88–2.84) 20+ 39 33 1.23 (0.72–2.11) 74 39 2.71 (1.64–4.50) Duration of smoking (years) Never 92 98 1.00 65 92 1.00 1–9 26 25 1.07 (0.54–2.11) 30 26 1.79 (0.89–3.60) 10–19 43 46 1.02 (0.61–1.72) 63 43 1.97 (1.17–3.32) 20+ 20 34 0.63 (0.32–1.23) 41 20 3.13 (1.57–6.23) Average no. of cigarettes/day when smoking Never 92 98 1.00 65 92 1.00 1–10 33 38 0.89 (0.51–1.56) 29 33 1.36 (0.73–2.51) 11–16 28 38 0.77 (0.44–1.36) 45 28 2.20 (1.24–3.89) 17+ 28 29 1.10 (0.60–2.00) 60 28 3.06 (1.77–5.31) a b c d e Stratified by 5-year age group; P < 0.0005; P for trend < 0.0005 among current smokers; P for trend < 0.0005; P for trend < 0.0001 British Journal of Cancer (2000) 83(11), 1565–1572 © 2000 Cancer Research Campaign Manchester case–control study of CIN31569 Table 4 Univariate odds ratios for different oral contraceptive variables HPV+ve Controls vs HPV–ve Controls HPV+ve Cases vs HPV+ve Controls +ve –ve OR 95% Cl Ca Con OR 95%Cl Current oral contraceptive use Never 35 38 1.00 32 35 1.00 Ex 96 116 0.78 (0.43–1.43) 108 96 1.15 (0.63–2.10) Current 50 49 0.95 (0.48–1.89) 59 50 1.28 (0.66–2.50) Total months of use Never 35 38 1.00 32 35 1.00 1–47 38 51 0.66 (0.33–1.33) 42 38 1.19 (0.58–2.43) 48–95 56 55 0.94 (0.48–1.84) 43 56 0.76 (0.38–1.53) 96+ 52 59 0.87 (0.45–1.67) 82 52 1.52 (0.80–2.88) Months since first started use Never 35 38 1.00 32 35 1.00 1–95 47 40 1.14 (0.48–2.75) 33 47 0.52 (0.21–1.28) 96–191 56 79 0.60 (0.30–1.21) 76 56 1.23 (0.61–2.48) 192+ 43 46 0.93 (0.47–1.84) 58 43 1.41 (0.71–2.79) Use of any progesterone-only pill Never 35 38 1.00 32 35 1.00 Ever 17 9 1.67 (0.62–4.48) 17 17 1.29 (0.48–3.44) a b Stratified by 5-year age group; Excludes women who have been on combined oral contraceptives, but never a progesterone-only pill Table 5 Adjusted odds ratios for HPV infection among controls, and CIN3 among those infected HPV+ve Controls vs HPV–ve Controls HPV+ve Cases vs HPV+ve Controls +ve –ve OR 95% Cl Ca Co OR 95%Cl Age at first intercourse ≤16 52 57 1.00 87 52 1.00 17–20 102 112 1.08 (0.64–1.83) 98 102 0.57 (0.35–0.94) 21+ 25 31 1.00 (0.45–2.23) 14 25 0.31 (0.13–0.75) Total number of sexual partners 1 39 83 1.00 39 39 1.00 2–5 100 93 2.15 (1.30–3.54) 121 100 0.88 (0.50–1.57) 6+ 40 24 3.89 (1.99–7.62) 39 40 0.64 (0.32–1.28) Years since start of latest regular relationship <2 50 21 1.00 24 50 1.00 2–5 56 36 0.77 (0.39–1.53) 48 56 1.72 (0.88–3.35) c c 6+ 73 143 0.24 (0.12–0.47) 127 73 4.94 (2.51–9.71) Current daily smoking habit Never 91 96 1.00 65 91 1.00 Ex 14 26 0.69 (0.31–1.53) 22 14 1.69 (0.76–3.75) 1–19 35 45 0.79 (0.44–1.41) 38 35 1.48 (0.79–2.76) 20+ 39 33 0.94 (0.52–1.70) 74 39 2.57 (1.49–4.45) Ever had a spontaneous abortion No 150 182 1.00 169 150 1.00 Yes 29 18 2.59 (1.28–5.21) 30 29 0.84 (0.45–1.56) Odds ratios are stratified by age and also adjusted for the other variables in the table, except: number of partners is not adjusted for b c d years since start of latest regular relationship (see text). P for trend < 0.005; P for trend < 0.0005; P for trend (in current smokers) < 0.001; P < 0.01 age at first intercourse, long duration of the latest regular sexual number of cigarettes smoked per day. Modelling the variables relationship, and smoking. A moderate association with educa- simultaneously showed both dose measures to be important, tional level and parity disappeared after adjustment for these vari- although number of cigarettes per day was a stronger predictor of ables. These findings are in complete contrast to the risk factors for risk. In none of the analyses was an association found between risk infection per se. The association between disease and time since of HPV infection and smoking. start of the most recent relationship, which is very strong Table 4 shows the results of further investigations of oral contra- and the inverse of that seen in the previous analysis, suggests ceptive use. Among the controls there was no indication of any that CIN3 is associated with longstanding persistent HPV infection. association between OCs and HPV infection. Point estimates for Table 3 shows the results of further analyses of different the highest categories of each measure of use were slightly raised measures of smoking habit. Among HPV-positive women there in CIN3 cases compared with HPV-positive controls, but none was strong evidence for a disease association with highly signific- reached conventional levels of significance and there were no ant increasing trends in risk with increasing duration of smoking or significant trends. © 2000 Cancer Research Campaign British Journal of Cancer (2000) 83(11), 1565–1572 1570 JM Deacon et al Table 6 Risk of CIN3 by HPV genotype among infected women those infected (OR 4.94) in women who had not acquired a new partner in the last 6 years. The corresponding OR for CIN3 using HPV+ve Cases vs HPV+ve Controls the HPV-negative controls would be the product of these estim- Ca Con OR 95% Cl ates, which is close to unity. These highly significant opposite effects are informative in relation to the natural history of HPV HPV Type infection and neoplasia, but they illustrate a potentially serious 16 132 55 1.00 b error in the analysis of such data. If we had chosen random 16 Related 37 33 0.48 (0.27–0.86) 18 & Related 20 31 0.27 (0.14–0.52) controls irrespective of their HPV status, most of whom would Other 10 62 0.06 (0.03–0.13) be HPV-negative, an unadjusted analysis would have given the correct result that recent sexual behaviour has little effect on a b c Odds ratios stratified by 5-year age group; 31, 33, 35, 52, 58; 18, 39, 45, the CIN3 risk; but the same analysis stratified by HPV status 59; all others, including generic probe-positive but type unidentified. When would be dominated by the comparison of CIN3 cases against multiple HPV types were detected women have been categorized by their HPV-positive controls and would indicate that a woman’s risk of highest risk virus according to the ranking in the table developing CIN3 decreases abruptly when she begins a new rela- tionship. This curious statistical artefact arises because most HPV infections are transient (Hinchliffe et al, 1995) but those preceding Table 5 shows adjusted odds ratios for the acquisition of HPV CIN3 diagnosis are persistent (Remmink et al, 1995). A transient infection and for the development of CIN3 among those infected, infection acquired from a new partner is usually harmless, at least for all variables significantly associated with either outcome in a in the short term, but the minority of women in long-standing rela- multivariate model. The estimates are mutually adjusted, except tionships who are still infected have persistent disease, and are that number of partners is not adjusted for time since the beginning thus at high risk of developing CIN3. of the latest sexual relationship. This is because in this data set, Over 99% of the women we interviewed were willing, in confid- given monogamy, close age stratification and age at first inter- ence, to discuss their sexual history. This, together with the very course, the date of the start of the (single) relationship is closely low and comparable refusal rate among both cases and controls predictable. The results are little different from those in Table 2 leads us to anticipate minimal information bias in the study. A and still show a striking division between factors related to HPV potential bias, however, is the differential loss of mobile first choice infection and those predictive of CIN3 in infected women. controls (movers): significantly more HPV-positive controls (27%) The risk of CIN3 by HPV genotype among infected women is than HPV-negative controls (12%) or CIN3 cases (11%) had moved shown in Table 6. HPV16, by far the most prevalent single virus and were still untraced at the end of the study. It appears likely that type, has been analysed separately. Other viruses have been have women who move frequently and who do not re-register with a new been grouped according to their phylogeny based on nucleotide doctor are less likely to be in a permanent or long-term relationship. and amino acid sequence alignments of E6 sequences as published We would anticipate that any bias caused by this selection, there- by the Human Papillomavirus Database at Los Alamos National fore, would tend to weaken all the duration effects we found and so Laboratory (http//hpv-web.lanl.gov) (van Ranst et al, 1993). The our relative risk estimates are probably conservative. risk of CIN3 was far greater with HPV16 infection than with any Our analysis of CIN3 incidence in the whole Manchester cohort other type, including related genotypes. (Peto et al, in preparation) shows that CIN3 can develop quite rapidly in cytologically normal HPV carriers. Such women have a DISCUSSION risk of CIN3 being detected at the following smear of between 5 Our most remarkable finding is the striking difference between the and 10%. This observation, together with the findings here, indi- sexual risk factors that predict HPV infection and those that cates that the natural history of CIN3 often includes a long period predict CIN3 among infected women. A woman’s likelihood of of cytologically undetectable HPV infection. having a detectable HPV infection depends only on her number of The significant association between HPV infection and induced sexual partners and how recently she has acquired a new partner. abortion shown in Table 2 disappeared after adjustment for the The number of partners presumably determines the probability variables shown in Table 5, which reduced this OR from 2.35 that she has ever been infected. Most relationships would have (P<0.05) to 1.38 (not significant). Similar findings were previously ended many years earlier, and the fact that they still predict her risk reported by Karlsson et al. (1995). For spontaneous abortion, of a usually transient infection suggests that many such episodes however, the same adjustment increased the OR from 2.24 are recurrences of latent long-standing infection. In contrast, HPV (P<0.05) to 2.59 (P<0.01). This association between current HPV acquired from a new partner is likely to be an initial infection infection and previous spontaneous abortion supports the inference rather than a recurrence. The main risk factor for CIN3 among that many prevalent HPV infections are persistent or recurrent infected women is age at first intercourse, presumably because rather than newly acquired. duration of exposure is the main risk factor for neoplastic progres- Our results show no clear association of oral contraceptive use sion. The fact that number of partners does not increase the CIN3 with either HPV infection or disease. This is in contrast to a recent risk suggests that once a woman has been infected the risk is not study (Ylitalo et al, 1999) where current use was associated with a increased by reinfection. The CIN3 risk in infected women who highly significant four-fold increase in risk of CIN3. From Table 4 have not had a recent new partner is presumably high because it can be seen that HPV-infected women who used the pill for 8 diagnosis of CIN3 is often preceded by a period of persistent HPV years or more, and those whose first use was more than 8 years detectability which may well be an effect of subclinical neoplastic earlier, were at marginally increased although not significant risk progression rather than its cause. This risk factor raises a novel of CIN3. We have therefore analysed duration of use more than 8 epidemiological difficulty. We observed a marked protective effect years before diagnosis. The relative risk was 1.67 (1.03–2.72) in for HPV infection (OR 0.24) but an increased risk for CIN3 among ever users, but there was no significant trend with duration of use. British Journal of Cancer (2000) 83(11), 1565–1572 © 2000 Cancer Research Campaign Manchester case–control study of CIN31571 Breslow NE and Day NE (1980) Statistical Methods in Cancer Research. Vol 1 – This risk was reduced to 1.47 (0.89–2.43) when duration of latest The analysis of case-control studies. IARC Scientific Publications: Lyon relationship, which is correlated with long-term pill use, was Brinton LA (1992) Epidemiology of cervical cancer – overview. In The included in the model, and further reduced to 1.24 (0.72–2.15) epidemiology of human papillomavirus and cervical cancer. Munoz N, Bosch when adjusted for the other variables listed in Table 5. FX, Shah KV and Meheus A (eds), pp 3–23. International Agency for Research on Cancer: Lyon The evidence that smoking increases the risk of CIN3 and Evander M, Edlund K, Gustafsson A, Jonsson M, Karlsson R, Rylander E and cervical cancer, which has been accumulating over the last 25 Wadell G (1995) Human papillomavirus infection is transient in young women: years, has recently been reviewed by Szarewski and Cuzick a population-based cohort study. J Infect Dis 171: 1026–1030 (1998). They concluded that the increased risk seen in most studies Hildesheim A, Gravitt P, Schiffman MH, Kurman RJ, Barnes W, Jones S, Tchabo was reduced but not eliminated by adjustment for age at first inter- J-G, Brinton LA, Copeland C, Epp J and Manos MM (1993) Determinants of genital human papillomavirus infection in low-income women in Washington course and number of sexual partners, the residual risk remaining DC. Sex Transm Dis 20: 279–285 at or above two-fold in current smokers and showing a dose– Hinchliffe SA, van Velzen D, Korporaal H, Kok PL and Boon ME (1995) Transience response in many studies. The causal basis of the link, however, is of cervical HPV infection in sexually active young women with normal still controversial because of the marked correlation between cervicovaginal cytology. Br J Cancer 72: 943–945 Ho GYF, Bierman R, Beardsley L, Chang CJ and Burk RD (1998) Natural history of smoking and early sexual behaviour. In our study, for example, the cervicovaginal papillomavirus infection in young women. N Engl J Med 338: proportion of controls whose age at first sexual intercourse was 16 423–428 or less was 38% among women who had ever smoked and 19% IARC (1995) Monographs on the evaluation of carcinogenic risks to humans. among never smokers. The prevalence of HPV infection was also Vol 64 Human papillomaviruses. International Agency for Research on Cancer: increased among smokers in several studies, although the associa- Lyon Karlsson R, Jonsson M, Edlund K, Evander M, Gustavsson A, Boden E, Rylander E tion was reduced by adjustment for sexual variables (Ley et al, and Wadell G (1995) Lifetime number of partners as the only independent risk 1991; Bauer et al, 1993; Olsen et al, 1998). Szarewski and Cuzick factor for human papillomavirus infection: a population-based study. Sex (1998) noted that adjustment for HPV infection further reduced the Transm Dis 22: 119–127 effect of smoking on cervical neoplasia in some studies, raising Layde PM (1989) Smoking and cervical cancer: cause or coincidence? JAMA 261: 1631–1633 further doubts about the causal role of smoking (Morrison et al, Ley C, Bauer HM, Reingold A, Schiffman MH, Chambers JC, Tashiro CJ and 1991; Olsen et al, 1998). The independence of smoking and HPV Manos MM (1991) Determinants of genital human papillomavirus infection in infection in this study and the consistent and highly significant young women. J Natl Cancer Inst 83: 997–1003 dose-response for CIN3 compared with HPV-infected controls Manos MM, Ting Y, Wright DK, Lewis AJ, Broker TR and Wolinsky SM (1989) provide strong evidence that smoking acts synergistically with The use of polymerase chain reaction amplification for the detection of genital human papillomaviruses. Molecular Diagnostics of Human Cancer: Cancer HPV to cause cervical neoplasia. Cells 7: 209–214 Melkert PWJ, Hopman E, van den Brule AJC, Risse EKJ, van Diest PJ, Bleker OP, Helmerhorst T, Schipper MEI, Meijer CJLM and Walboomers JMM (1993) ACKNOWLEDGEMENTS Prevalence of HPV in cytomorphologically normal cervical smears, as determined by the polymerase chain reaction, is age-dependent. Int J Cancer Our thanks are due to all the clinic and laboratory staff who helped 53: 919–923 to construct the Manchester cohort, and to Heidi Bauer, Catherine Morrison EAB, Ho GYF, Vermund SH, Goldberg GL, Kadish AS, Kelley KF and Greer, Patti Gravitt and Cosette Wheeler for the provision of Burk RD (1991) Human papillomavirus infection and other risk factors for reagents and probes, and for their help in setting up our HPV labor- cervical neoplasia: a case-contol study. Int J Cancer 49: 6–13 atory. Most of all we thank the women, cases and controls, who so Olsen AO, Dillner J, Skrondal A and Magnus P (1998) Combined effect of smoking and human papillomavirus type 16 infection in cervical carcinogenesis. willingly agreed to participate and give interviews. Janet Wilson, Epidemiology 9: 346–349 together with Wendy Binns, performed the interviews, Michelle Phillips AN and Davey Smith G (1994) Cigarette smoking as a potential cause of Haywood and N Elanko ran the HPV lab, and Jane Hatch and cervical cancer: has confounding been controlled? Int J Epidemiol 23: 42–49 Doreen Lewis managed the data. Remmink AJ, Walboomers JMM, Helmerhorst TJM, Voorhorst FJ, Rozendaal L, Risse EKJ, Meijer CJLM and Kenemans P (1995) The presence of persistent The study was supported and funded by the Cancer Research high-risk HPV genotypes in dysplastic cervical lesions is associated with Campaign through project grants SP2285/0401 and SP2285/0501. progressive disease: natural history up to 36 months. Int J Cancer 61: 306–311 Schiffman MH (1992) Recent progress in defining the epidemiology of human papillomavirus infection and cervical neoplasia. J Natl Cancer Inst 84: REFERENCES 394–398 Szarewski A and Cuzick J (1998) Smoking and cervical neoplasia: a review of the Bauer HM, Ting Y, Greer CE, Chambers JC, Tashiro CJ, Chimera J, Reingold A and evidence. J Epidemiol Biostat 3: 229–256 Manos MM (1991) Genital human papillomavirus infection in female university students as determined by a PCR-based method. JAMA 265: van Ranst MA, Tachezy R, Delius H and Burk RD (1993) Taxonomy of the human 472–477 papillomaviruses. Papillomavirus Reports 4: 61–65 Bauer HM, Greer CE and Manos MM (1992) Determination of genital human Walboomers JMM, Jacobs MV, Manos MM, Bosch FX, Kummer JA, Shah KV, papillomavirus infection by consensus PCR amplification. In Diagnostic Snijders PJF, Peto J, Meijer CJLM and Munoz N (1999) Human papillomavirus molecular pathology: a practical approach. Herrington CS and McGee JOD is a necessary cause of invasive cervical cancer worldwide. J Pathol 189: (eds), pp 131–152. Oxford University Press: Oxford 12–19 Bauer HM, Hildesheim A, Schiffman MH, Glass AG, Rush BB, Scott DR, Cadell Wheeler CM, Parmenter CA, Hunt WC, Becker TM, Greer CE, Hildesheim A and DM, Kurman RJ and Manos MM (1993) Determinants of genital human Manos MM (1993) Determinants of genital human papillomavirus infection papillomavirus infection in low-risk women in Portland, Oregon. Sex Transm among cytologically normal women attending the University of New Mexico Dis 20: 274–278 Student Health Center. Sex Transm Dis 20: 286–289 Bosch FX, Manos MM, Munoz N, Sherman M, Jansen AM, Peto J, Schiffman MH, Ylitalo N, Sorensen P, Josefsson A, Frisch M, Sparen P, Ponten J, Moreno V, Kurman R and Shah KV. International Biological Study on Cervical Gyllensten U, Melbye M and Adami H-O (1999) Smoking and oral Cancer (IBSCC) Study Group (1995) Prevalence of human papillomavirus in contraceptives as risk factors for cervical carcinoma in situ. Int J Cancer 81: cervical cancer: a worldwide perspective. J Natl Cancer Inst 87: 796–802 357–365 © 2000 Cancer Research Campaign British Journal of Cancer (2000) 83(11), 1565–1572 1572 JM Deacon et al APPENDIX The Manchester UK cohort: clinical collaborators GP Practices: Drs D Bodey, S Hollingshead and T Rashid, Wilmslow Road, Fallowfield; Drs H Burgess, S Goodman and HC Sutherland, Mauldeth Road, Fallowfield; Drs K Checkland, M Jones and K Wells, Church Street, Marple, Stockport; Dr DN Riley, Robins Lane Medical Centre, Bramhall; Drs E Tierney, JCV Gillighan, JF Downie and AP Morris, Whitworth Medical Centre, Rochdale; Partners of the Northenden Group Practice, Palatine Road, Withington; Partners of the Robert Darbyshire Practice, Rusholme Health Centre Family planning clinics: Adswood Clinic, Stockport; Ancoats Hospital; Brinnington Clinic, Stockport; Cheadle Health Clinic, Stockport; Corporation Road Clinic, Eccles; Grasmere Street Health Centre, Leigh; Hazel Grove Clinic, Stockport; Heaton Norris Clinic, Stockport; Higher Broughton Health Centre, Salford; Hope Hospital, Salford; Lanceburn Health Centre, Salford; Langworthy Clinic, Salford; Little Hulton Clinic, Worsley; Liverpool Road Clinic, Hindley; Longsight Health Centre; Lower Broughton Clinic, Salford; Maple Clinic, Stockport; North Reddish Clinic, Stockport; Northern Hospital, Cheetham; Offerton Clinic Stockport; Offerton Green Clinic, Stockport; Partington Lane Clinic, Swinton; Romiley Health Centre, Stockport; Shaw Health Clinic, Stockport; St Mary’s Hospital; Stepping Hill Clinic, Stockport; The Palatine Centre, Palatine Road, Withington; Woodley Clinic, Stockport Screening clinics: Abbey Hey Clinic, Gorton; Alexandra Park Health Centre; Ancoats Community Clinic; Assheton Road Clinic, Newton Heath; Atherton Clinic, Wigan; Baguley Clinic; Beech Hill Health Centre, Wigan; Beswick Health Centre; Bevendon Square Clinic, Salford; Boothtown Clinic; Bramhall Clinic, Stockport; Bredbury Clinic, Stockport; Brookfield Clinics, Stockport; Brunswick Clinic; Burley House Clinic, Stockport; Central Drive Clinic, Crumpsall; Charlestown Health Centre, Blackley; Child Health Centre, Benchill; Clayton Health Centre; College Road Clinic, Leigh; Corporation Road Clinic, Eccles; Crumpsall Clinic; Derby Road Clinic, Golborne; Derbyshire House Clinic; Gorton Combined Clinic, West Gorton; Grasmere Street Health Centre, Leigh; Haig Road Clinic, Aspull; Harpurhey Health Centre; Hazel Grove Clinic, Stockport; Heaton Norris Clinic, Stockport; Hulme Clinic; Irlam Health Centre; Levenshulme Health Centre; Little Hulton Clinic, Worsley; Liverpool Road Health Centre, Hindley; Liverpool Street Clinic, Salford; Longshoot Lane Health Centre, Scholes; Lower Broughton Clinic, Salford; Monton Road Clinic, Eccles; Moss Side Health Centre; Newton Heath Health Centre; Nicholas Road Health Centre, Chorlton; North Reddish Clinic, Stockport; Offerton Clinic, Stockport; Ordsall Health Centre, Salford; Orrell Road Clinic, Wigan; Partington Lane Clinic, Swinton; Pemberton Clinic, Wigan; Plant Hill Clinic, Blackley; Platt Bridge Clinic, Wigan; Poplar Street Clinic, Tyldesley; Queens Road Clinic, Ashton-in-Makerfield; Romiley Clinic, Stockport; Smedley Street Clinic, Crumpsall; Standish Clinic, Wigan; Varley Street Clinic, Miles Platting; Walkden Clinic; Walmer Street Clinic, Rusholme; Wellwoman Clinic, Woodhouse Park; Wellwoman Clinic, Irlam; Wellwoman Clinic, Stockport; Wilmslow Road Clinic, Didsbury; Woodhouse Park Clinic, Wythenshawe British Journal of Cancer (2000) 83(11), 1565–1572 © 2000 Cancer Research Campaign http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png British Journal of Cancer Springer Journals

Sexual behaviour and smoking as determinants of cervical HPV infection and of CIN3 among those infected: a case–control study nested within the Manchester cohort

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Springer Journals
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Copyright © 2000 by The Author(s)
Subject
Biomedicine; Biomedicine, general; Cancer Research; Epidemiology; Molecular Medicine; Oncology; Drug Resistance
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0007-0920
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1532-1827
DOI
10.1054/bjoc.2000.1523
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Abstract

British Journal of Cancer(2000) 88(11), 1565–1572 © 2000 Cancer Research Campaign doi: 10.1054/ bjoc.2000.1523, available online at http://www.idealibrary.com on http://www.bjcancer.com Sexual behaviour and smoking as determinants of cervical HPV infection and of CIN3 among those infected: a case–control study nested within the Manchester cohort 1 1 2 2 1 1 1 JM Deacon, CD Evans, R Yule, M Desai, W Binns, C Taylorand J Peto 1 2 Section of Epidemiology, Institute of Cancer Research, 15 Cotswold Road, Belmont, Sutton, Surrey, SM2 5NG; Department of Cytology, Christie Hospital NHS Trust, Wilmslow Road, Withington, Manchester, M20 4BX, UK Summary To distinguish risk factors for acquisition of cervical human papillomavirus (HPV) infection from the determinants of n eoplasia among infected individuals we have conducted a three-arm case-control study nested within a large population-based cohort of women (the Manchester cohort) screened for HPV at entry using L1 consensus primer PCR. The study includes 181 HPV-positive controls who did not develop high-grade cervical intraepithelial neoplasia (CIN3) during follow-up, 203 HPV-negative controls, and 199 HPV-positive cases with histologically confirmed CIN3. Detailed information on sexual, reproductive and gynaecological history, oral contraceptive use and smoking was obtained at face-to-face interview. There was a striking division between risk factors for infection and those predictive of disease. Comparing the HPV-positive against the HPV-negative controls, the only risk factors for infection were number of sexual partner s (OR for six or more = 3.89; 95% Cl = 1.99–7.62), a relatively recent new sexual relationship (OR for a new partner within the previous 2 years = 4.17; 95% Cl = 2.13–8.33), and a history of previous miscarriage (OR = 2.59; 95% Cl = 1.28–5.21). The determinants of CIN3 among infe cted women were, in contrast, early age at first intercourse (OR for 16 years old or less = 3.23; 95% Cl = 1.33–7.69), a long time since starting a new sexual relationship (OR for 6 years or more = 4.94; 95% Cl = 2.51–9.71), and cigarette smoking, with strong evidence for a dose– response (OR for current smoking habit 20+ per day = 2.57; 95% Cl = 1.49–4.45). Oral contraceptive use was not significantly associated with either HPV infection or CIN3. © 2000 Cancer Research Campaign http://www.bjcancer.com Keywords: cervical neoplasia; CIN3; HPV; sexual behaviour; smoking Human papillomavirus (HPV) infection has now been accepted as we have conducted a three-arm interview-based case-control study the primary cause of cervical neoplasia (Schiffman, 1992; Bosch in which the basis for case and control selection was HPV infec- et al, 1995; IARC, 1995; Walboomers et al, 1999). Oncogenic tion as well as disease status. The study was nested in a large popu- genital HPVs, however, are highly prevalent in many populations lation-based cohort undergoing routine cervical screening in the where CIN3 and cervical cancer remain relatively rare (Bauer city of Manchester, where cervical cell samples for HPV analysis et al, 1991, 1993; Hildesheim et al, 1993; Melkert et al, 1993; had been collected from all participants at entry (Peto et al, in Wheeler et al, 1993) and natural history studies have shown that preparation). It includes 199 cases of histologically confirmed most infections are transient and not associated with detectable CIN3 diagnosed after entry to the cohort in women known to be cytological abnormality (Evander et al, 1995; Hinchliffe et al, HPV-positive, 181 women infected with HPV but without CIN3 1995; Ho et al, 1998). The reasons for this variable natural history and 203 HPV-negative controls. are poorly understood but it has been generally assumed that other causes or co-factors must be important for the development of neoplasia in HPV-infected individuals. In addition to sexual MATERIALS AND METHODS activity, case-control studies have identified a number of other possible factors including high parity, the presence of other chronic The cohort genital infections, cigarette smoking and oral contraceptive use The recruitment of the Manchester cohort and the methods of data (Brinton, 1992). These effects may, however, be due at least partly collection and follow-up are described elsewhere (Peto et al, in to the correlation between sexual behaviour and other risk factors, preparation). Briefly, between 1987 and 1993, in collaboration and the failure in most studies to control adequately for con- with over 100 general practitioners and screening clinics in the founding by HPV (Layde, 1989; Phillips and Davey Smith, Greater Manchester area who used the Christie Hospital cytology 1994). service, we collected 78 062 cervical cell samples from 61 570 In an attempt to resolve these problems, and to distinguish women attending for routine screening. The cell samples were between risk factors for the acquisition of cervical HPV infection obtained by elution from spatulas used to take Pap smears. There and co-factors for the development of CIN3 among those infected, was no age restriction for participants. All samples were allocated a unique identifying number (ID) and were stored in buffer Received 8 June 2000 at –40˚C. Through regular data linkage of the study IDs with the Revised 31 August 2000 main laboratory database, the screening records of cohort mem- Accepted 31 August 2000 bers and the histology results of any cervical biopsies have been Correspondence to: JM Deacon updated. 1565 1566 JM Deacon et al Case-control study – eligibility criteria generic probe but negative to all type-specific probes were desig- nated as positive, but untyped. This study was restricted to white women of any age who had been routinely and satisfactorily screened at least once through Interviews the Christie laboratory prior to entry to the main cohort, and who had had a smear and concurrent spatula cell sample (termed The ID numbers of potentially eligible cases and controls with ‘spatula’) taken on or after 1 July 1988, that were diagnostically adequate HPV results were identified to the Christie Hospital, adequate both for cytology and for PCR. These samples were the where eligibility was checked as far as was possible from routine ‘index’ smear and spatula that defined a woman’s age and HPV records. A senior clinician (RY) then contacted the general practi- status. Women were excluded if they had had a hysterectomy, a tioner of each woman to obtain approval for an interviewer to previous malignancy or previous CIN3, if they suffered from contact the patient and invite her to participate. Between August serious psychiatric illness, or if they were known to have moved 1990 and July 1996 interviews were conducted in the women’s out of the study area since entry to the cohort. Because of the homes by one of two trained interviewers using a structured temporary nature of their residence in the city, students at questionnaire. Information collected included demographic data, Manchester’s several universities and colleges of further educa- menstrual, reproductive and gynaecological history, sexual history tion were also excluded. The cytological result of the index and information on smoking habits. Sexual, contraceptive and smear was not a criterion for determining either case or control reproductive histories were collected on a calendar with a record eligibility. for every month of a woman’s life from the age of menarche (or first intercourse, whichever was earlier) up to the date of index Case identification smear. Inconsistent data were rechecked with study participants by telephone. The data were then anonymized, coded and entered on Cases were all those women in the cohort, eligible by the above computer. criteria, who developed histologically diagnosed CIN3 within 3 years of their index smear. Statistical analysis Control selection All risk factor analyses relate to exposures prior to the index spatula date. Two separate analyses were performed. The first, Two control groups of approximately equal size were identified, analysing risk factors for the acquisition of HPV infection, the first consisting of women found, on PCR screening of their compared HPV-positive controls with HPV-negative controls. The index spatulas, to be HPV-positive, and the second consisting of second, analysing risk factors for the development of CIN3 among HPV-negative women. No control had CIN3 diagnosed at any time those infected with HPV, compared the CIN3 cases with the HPV- during her follow-up but women with CIN1 or 2 were not positive controls. The age stratification of the study design was excluded. Potential controls were identified through stratified maintained in univariate and multivariate conditional logistic random sampling. All the spatulas collected since 1 July 1988 regression analyses (Breslow and Day, 1980) using the STATA for from eligible women in the cohort were stratified by date (1-year Windows® program package. Relative risks were estimated as periods: 1 July 1988 to 30 June 1989, etc) and age of the woman at odds ratios (OR) with approximate 95% confidence intervals. χ the time (5-year age groups: < 20, 20–24, 25–29, etc). Within each values for differences are Mantel–Haenszel corrected. Tests for age/period stratum spatulas were submitted for HPV testing in linear trend of log odds were performed by scoring categories of random order. Testing continued until the number of HPV-positive exposure and fitting them as continuous variables. All P values are spatulas identified roughly equalled the number of cases in each two-sided. stratum. In instances where a woman had two or more spatulas independently selected for random testing, the earlier was defined as her index. Controls approached for interview were the first RESULTS HPV-positive and HPV-negative women in their stratum to be identified by the random HPV testing. 315 potential cases and 583 potential controls were identified by the HPV laboratory and determined from the cytology database and GP records to be eligible. Of these, 232 cases (74%) and 384 HPV detection and genotyping controls (181 HPV-positive and 203 HPV-negative, total 66%) HPV DNA in the index spatulas of cases and the random potential Table 1 Age distributions of interviewed women by case/control status controls was assayed at the Institute of Cancer Research using L1 Age HPV+ve CIN3 Cases HPV+ve Controls HPV–veControls consensus PCR amplification with the MY09/MY11 primer pair as (n) (%) (n) (%) (n) (%) described in detail elsewhere (Bauer et al, 1992; Manos et al, 1989). Concurrent amplification of a 286 bp human β-globin frag- < 20 4 (2.0) 7 (3.8) 5 (2.5) ment was used as an internal control, its failure to amplify desig- 20–24 19 (9.6) 19 (10.5) 21 (10.3) nating a sample inadequate. Consensus HPV-product was detected 25–29 52 (26.1) 47 (26.0) 49 (24.1) using a biotinylated generic probe and enhanced chemilumines- 30–34 49 (24.6) 40 (22.1) 47 (23.2) 35–39 32 (16.1) 29 (16.0) 32 (15.8) cence (Amersham International). Positive samples were hybrid- 40–44 23 (11.6) 19 (10.5) 21 (10.3) ized with type-specific oligonucleotide probes to determine the 45–49 7 (3.5) 9 (5.0) 12 (5.9) virus genotypes present (types 6/11/42 (mixed), 16, 18, 26, 31, 33, 50+ 13 (6.5) 11 (6.1) 16 (7.9) 35, 39, 40, 45, 51, 52, 53, 54, 55, 56, 57, 58, 59, 73, ME180, PAP88 Total 199 181 203 (HPV66), PAP155, PAP291 and W13B). Samples positive to the British Journal of Cancer (2000) 83(11), 1565–1572 © 2000 Cancer Research Campaign Manchester case–control study of CIN31567 Table 2 Characteristics of cases and controls: univariate odds ratios for HPV infection among controls, and CIN3 among those infected HPV+ve Controls vs HPV ve Controls HPV+ve Cases vs HPV+ve Controls +ve –ve OR 95% Cl Ca Con OR 95%CI Marital status Married 83 130 1.00 92 83 1.00 Cohabiting 26 19 2.02 (1.03–3.98) 35 26 1.22 (0.67–2.24) Wid/Sep/Div 35 20 2.59 (1.40–4.79) 36 35 0.83 (0.47–1.47) Single 37 34 1.61 (0.88–2.94) 36 37 0.95 (0.52–1.71) Age left full-time education 13–15 44 52 1.00 68 44 1.00 16–18 104 121 0.88 (0.52–1.52) 110 104 0.66 (0.39–1.12) 19–21 19 18 1.10 (0.50–2.43) 13 19 0.40 (0.17–0.93) 22+ 14 12 1.24 (0.51–3.02) 8 14 0.34 (0.13–0.90) Age at menarche ≤11 24 45 1.00 37 24 1.00 12 27 28 1.68 (0.81–3.51) 42 27 1.03 (0.51–2.09) 13 57 56 1.85 (1.00–3.45) 50 57 0.55 (0.27–1.04) 14 45 43 1.90 (0.99–3.62) 39 45 0.53 (0.27–1.04) 15+ 28 31 1.61 (0.79–3.28) 31 28 0.71 (0.34–1.47) Number of full-term pregnancies 0 71 64 1.00 63 71 1.00 1 33 37 0.79 (0.44–1.42) 46 33 1.57 (0.88–2.77) 2 51 68 0.68 (0.40–1.17) 49 51 1.13 (0.64–1.99) 3+ 26 34 0.69 (0.35–1.38) 41 26 1.90 (0.94–3.85) Age at first birth 15–19 28 35 1.00 41 28 1.00 20+ 82 104 0.93 (0.51–1.71) 95 82 0.74 (0.41–1.33) Ever had a spontaneous abortion No 152 185 1.00 169 152 1.00 Yes 29 18 2.24 (1.17–4.30) 30 29 0.95 (0.54–1.68) Ever had an induced abortion No 154 189 1.00 176 154 1.00 Yes 27 14 2.35 (1.18–4.67) 23 27 0.75 (0.41–1.36) Age at first intercourse ≤16 52 58 1.00 87 52 1.00 17–20 104 113 1.08 (0.67–1.74) 98 104 0.51 (0.32–0.80) 21+ 25 32 0.90 (0.45–1.84) 14 25 0.25 (0.11–0.57) Total number of sexual partners 1 39 83 1.00 39 39 1.00 2–5 100 93 2.28 (1.40–3.70) 121 100 1.24 (0.72–2.12) 6+ 40 25 3.52 (1.84–6.76) 39 40 0.96 (0.50–1.84) Number of regular partners 1 47 93 1.00 46 47 1.00 2 50 57 1.79 (1.06–3.04) 82 50 1.66 (0.96–2.88) 3 49 26 3.82 (2.07–7.05) 39 49 0.82 (0.45–1.51) 4+ 34 26 2.65 (1.41–4.99) 32 34 0.91 (0.48–1.75) Years since start of latest regular relationship <2 50 21 1.00 24 50 1.00 2–5 56 37 0.72 (0.37–1.39) 48 56 1.65 (0.87–3.13) h h 6+ 74 144 0.19 (0.10–0.35) 127 74 4.06 (2.21–7.44) Ever had a sexually transmitted disease No 100 108 1.00 102 100 1.00 Yes 81 95 0.91 (0.61–1.37) 97 81 1.16 (0.77–1.74) Ever had a partner with genital warts No 170 199 1.00 187 170 1.00 Yes 11 4 3.01 (0.95–9.60) 12 11 1.04 (0.44–2.42) Months using barrier contraception 0 101 95 1.00 110 101 1.00 1–12 28 26 1.00 (0.55–1.84) 29 28 0.91 (0.50–1.64) 13–48 24 38 0.59 (0.33–1.06) 32 24 1.20 (0.66–2.19) 49+ 28 44 0.64 (0.36–1.14) 28 28 0.93 (0.51–1.70) Oral contraceptive use Never 35 38 1.00 32 35 1.00 Ex-user 96 116 0.78 (0.43–1.43) 108 96 1.15 (0.63–2.10) Current user 50 49 0.95 (0.48–1.89) 59 50 1.28 (0.66–2.50) Ever smoked No 92 98 1.00 65 92 1.00 Yes 89 105 0.90 (0.60–1.35) 134 89 2.20 (1.44–3.35) a b c d e f g h Stratified by 5-year age group; P < 0.05; P < 0.005; P < 0.0005; P for trend < 0.01; P for trend < 0.001; P for trend < 0.0005; P for trend < 0.0001 © 2000 Cancer Research Campaign British Journal of Cancer (2000) 83(11), 1565–1572 1568 JM Deacon et al were successfully interviewed. Among the interviewed cases there diagnosed as the direct result of an abnormal smear, and as this were 33 (14%) whose index spatula tested HPV-negative with the study was conducted early in the history of the cohort it was the L1 consensus primer system in spite of multiple attempts at ampli- index smear that was abnormal in each case, 91 (46%) showing fication under different conditions. These women did not differ severe dyskaryosis and 108 (54%) showing lower grades of from the HPV-positive cases with regard to age, cytology results, abnormality from atypia to moderate dyskaryosis. Among the social class, sexual, obstetric or contraceptive history. They were HPV-positive controls 22 (12%) had an index smear showing a 50% more likely than HPV-positive cases to have smoked but this transient mild abnormality that resolved within a year. A further 22 difference was not significant (χ = 0.63, P = 0.43). PCR using had persistent dyskaryosis and of these 11 had mild or moderate (1df) different primers has not yet been attempted with these samples dysplasia found at biopsy. Cytological abnormality was rare in and it is not clear whether they represent truly HPV-unrelated uninfected women, seven (3.5%) having transient dyskaryosis and CIN3 or if they are false-negatives. Because of this uncertainty one having reportedly persistent severe dyskaryosis that showed these cases have been excluded from the current analyses. The CIN1 on biopsy. data presented thus relate to 199 HPV-positive cases of CIN3, 181 Table 2 shows the distributions of cases and controls according HPV-positive controls and 203 HPV-negative controls. to selected characteristics and risk factors. Odds ratios are strati- The refusal rate was low and similar in cases and controls (15% fied by age according to the 5-year strata used for sampling, but and 13% respectively) and was unrelated to age. The main reason are otherwise unadjusted. In none of the analyses was there any for failure to interview was inability to trace the woman (18% evidence of heterogeneity of risk according to age. Among the overall). Untraced women were those whose medical records and controls risk of HPV infection was very strongly related to sexual health authority registers recorded them as being still resident, but behaviour. Both a woman’s total lifetime number of sexual part- whom the interviewers found not to be at their registered address. ners and her number of regular (longer than 3 months) relation- Among both cases and controls untraced women were signific- ships were highly predictive of risk (P for trend < 0.001). antly younger than those interviewed, reflecting the high mobility HPV-infected women were also much more likely than uninfected of a fit young urban population; χ for the difference between controls to have commenced a new regular relationship within the (1df) women under 30 and over 30 years was 8.67 (P < 0.005) for the past year. There was a moderately significant association between cases and 15.13 (P < 0.0005) for controls. Significantly more infection and history of miscarriage that was consistent in all controls (20%) than cases (11%) remained untraced at the end of analyses, remaining essentially unchanged after multivariate the study (χ for the difference = 12.81, P < 0.0005), probably regression (see Table 5). No other risk factors for HPV infection (1df) because the cases were under continuing medical surveillance and were identified. The associations between marital status, thera- hence their records were more accurate. Four controls (2 HPV peutic abortion and HPV infection disappeared after adjustment infected, 2 uninfected) who did not answer all the sexual questions for number of partners and recency of the latest relationship. There and one HPV negative control who reported no regular partners was no association in this data set between cervical HPV infection were excluded from multivariate analyses involving these and history of other sexually transmitted diseases (trichomonas, variables (see Table 5). genital warts, genital herpes or gonorrhoea), use of barrier Table 1 shows the age distributions of cases and controls. These contraception, oral contraceptives (OCs) or smoking. have been balanced by the stratified sampling process and reflect In the comparison of HPV-positive CIN3 cases against HPV- the age distribution of participating CIN3 cases. All the cases were positive controls the only important determinants of disease were Table 3 Univariate odds ratios for different smoking variables HPV+ve Controls vs HPV–ve Controls HPV+ve Cases vs HPV+ve Controls +ve –ve OR 95% Cl Ca Con OR 95%Cl Ever smoked No 92 98 1.00 65 92 1.00 Yes 89 105 0.90 (0.60–1.35) 134 89 2.20 (1.44–3.35) Current daily smoking habit (cigarettes/day) Never 92 98 1.00 65 92 1.00 Ex 15 27 0.66 (0.32–1.35) 22 15 2.14 (1.03–4.45) 1–19 35 45 0.79 (0.46–1.34) 38 35 1.58 (0.88–2.84) 20+ 39 33 1.23 (0.72–2.11) 74 39 2.71 (1.64–4.50) Duration of smoking (years) Never 92 98 1.00 65 92 1.00 1–9 26 25 1.07 (0.54–2.11) 30 26 1.79 (0.89–3.60) 10–19 43 46 1.02 (0.61–1.72) 63 43 1.97 (1.17–3.32) 20+ 20 34 0.63 (0.32–1.23) 41 20 3.13 (1.57–6.23) Average no. of cigarettes/day when smoking Never 92 98 1.00 65 92 1.00 1–10 33 38 0.89 (0.51–1.56) 29 33 1.36 (0.73–2.51) 11–16 28 38 0.77 (0.44–1.36) 45 28 2.20 (1.24–3.89) 17+ 28 29 1.10 (0.60–2.00) 60 28 3.06 (1.77–5.31) a b c d e Stratified by 5-year age group; P < 0.0005; P for trend < 0.0005 among current smokers; P for trend < 0.0005; P for trend < 0.0001 British Journal of Cancer (2000) 83(11), 1565–1572 © 2000 Cancer Research Campaign Manchester case–control study of CIN31569 Table 4 Univariate odds ratios for different oral contraceptive variables HPV+ve Controls vs HPV–ve Controls HPV+ve Cases vs HPV+ve Controls +ve –ve OR 95% Cl Ca Con OR 95%Cl Current oral contraceptive use Never 35 38 1.00 32 35 1.00 Ex 96 116 0.78 (0.43–1.43) 108 96 1.15 (0.63–2.10) Current 50 49 0.95 (0.48–1.89) 59 50 1.28 (0.66–2.50) Total months of use Never 35 38 1.00 32 35 1.00 1–47 38 51 0.66 (0.33–1.33) 42 38 1.19 (0.58–2.43) 48–95 56 55 0.94 (0.48–1.84) 43 56 0.76 (0.38–1.53) 96+ 52 59 0.87 (0.45–1.67) 82 52 1.52 (0.80–2.88) Months since first started use Never 35 38 1.00 32 35 1.00 1–95 47 40 1.14 (0.48–2.75) 33 47 0.52 (0.21–1.28) 96–191 56 79 0.60 (0.30–1.21) 76 56 1.23 (0.61–2.48) 192+ 43 46 0.93 (0.47–1.84) 58 43 1.41 (0.71–2.79) Use of any progesterone-only pill Never 35 38 1.00 32 35 1.00 Ever 17 9 1.67 (0.62–4.48) 17 17 1.29 (0.48–3.44) a b Stratified by 5-year age group; Excludes women who have been on combined oral contraceptives, but never a progesterone-only pill Table 5 Adjusted odds ratios for HPV infection among controls, and CIN3 among those infected HPV+ve Controls vs HPV–ve Controls HPV+ve Cases vs HPV+ve Controls +ve –ve OR 95% Cl Ca Co OR 95%Cl Age at first intercourse ≤16 52 57 1.00 87 52 1.00 17–20 102 112 1.08 (0.64–1.83) 98 102 0.57 (0.35–0.94) 21+ 25 31 1.00 (0.45–2.23) 14 25 0.31 (0.13–0.75) Total number of sexual partners 1 39 83 1.00 39 39 1.00 2–5 100 93 2.15 (1.30–3.54) 121 100 0.88 (0.50–1.57) 6+ 40 24 3.89 (1.99–7.62) 39 40 0.64 (0.32–1.28) Years since start of latest regular relationship <2 50 21 1.00 24 50 1.00 2–5 56 36 0.77 (0.39–1.53) 48 56 1.72 (0.88–3.35) c c 6+ 73 143 0.24 (0.12–0.47) 127 73 4.94 (2.51–9.71) Current daily smoking habit Never 91 96 1.00 65 91 1.00 Ex 14 26 0.69 (0.31–1.53) 22 14 1.69 (0.76–3.75) 1–19 35 45 0.79 (0.44–1.41) 38 35 1.48 (0.79–2.76) 20+ 39 33 0.94 (0.52–1.70) 74 39 2.57 (1.49–4.45) Ever had a spontaneous abortion No 150 182 1.00 169 150 1.00 Yes 29 18 2.59 (1.28–5.21) 30 29 0.84 (0.45–1.56) Odds ratios are stratified by age and also adjusted for the other variables in the table, except: number of partners is not adjusted for b c d years since start of latest regular relationship (see text). P for trend < 0.005; P for trend < 0.0005; P for trend (in current smokers) < 0.001; P < 0.01 age at first intercourse, long duration of the latest regular sexual number of cigarettes smoked per day. Modelling the variables relationship, and smoking. A moderate association with educa- simultaneously showed both dose measures to be important, tional level and parity disappeared after adjustment for these vari- although number of cigarettes per day was a stronger predictor of ables. These findings are in complete contrast to the risk factors for risk. In none of the analyses was an association found between risk infection per se. The association between disease and time since of HPV infection and smoking. start of the most recent relationship, which is very strong Table 4 shows the results of further investigations of oral contra- and the inverse of that seen in the previous analysis, suggests ceptive use. Among the controls there was no indication of any that CIN3 is associated with longstanding persistent HPV infection. association between OCs and HPV infection. Point estimates for Table 3 shows the results of further analyses of different the highest categories of each measure of use were slightly raised measures of smoking habit. Among HPV-positive women there in CIN3 cases compared with HPV-positive controls, but none was strong evidence for a disease association with highly signific- reached conventional levels of significance and there were no ant increasing trends in risk with increasing duration of smoking or significant trends. © 2000 Cancer Research Campaign British Journal of Cancer (2000) 83(11), 1565–1572 1570 JM Deacon et al Table 6 Risk of CIN3 by HPV genotype among infected women those infected (OR 4.94) in women who had not acquired a new partner in the last 6 years. The corresponding OR for CIN3 using HPV+ve Cases vs HPV+ve Controls the HPV-negative controls would be the product of these estim- Ca Con OR 95% Cl ates, which is close to unity. These highly significant opposite effects are informative in relation to the natural history of HPV HPV Type infection and neoplasia, but they illustrate a potentially serious 16 132 55 1.00 b error in the analysis of such data. If we had chosen random 16 Related 37 33 0.48 (0.27–0.86) 18 & Related 20 31 0.27 (0.14–0.52) controls irrespective of their HPV status, most of whom would Other 10 62 0.06 (0.03–0.13) be HPV-negative, an unadjusted analysis would have given the correct result that recent sexual behaviour has little effect on a b c Odds ratios stratified by 5-year age group; 31, 33, 35, 52, 58; 18, 39, 45, the CIN3 risk; but the same analysis stratified by HPV status 59; all others, including generic probe-positive but type unidentified. When would be dominated by the comparison of CIN3 cases against multiple HPV types were detected women have been categorized by their HPV-positive controls and would indicate that a woman’s risk of highest risk virus according to the ranking in the table developing CIN3 decreases abruptly when she begins a new rela- tionship. This curious statistical artefact arises because most HPV infections are transient (Hinchliffe et al, 1995) but those preceding Table 5 shows adjusted odds ratios for the acquisition of HPV CIN3 diagnosis are persistent (Remmink et al, 1995). A transient infection and for the development of CIN3 among those infected, infection acquired from a new partner is usually harmless, at least for all variables significantly associated with either outcome in a in the short term, but the minority of women in long-standing rela- multivariate model. The estimates are mutually adjusted, except tionships who are still infected have persistent disease, and are that number of partners is not adjusted for time since the beginning thus at high risk of developing CIN3. of the latest sexual relationship. This is because in this data set, Over 99% of the women we interviewed were willing, in confid- given monogamy, close age stratification and age at first inter- ence, to discuss their sexual history. This, together with the very course, the date of the start of the (single) relationship is closely low and comparable refusal rate among both cases and controls predictable. The results are little different from those in Table 2 leads us to anticipate minimal information bias in the study. A and still show a striking division between factors related to HPV potential bias, however, is the differential loss of mobile first choice infection and those predictive of CIN3 in infected women. controls (movers): significantly more HPV-positive controls (27%) The risk of CIN3 by HPV genotype among infected women is than HPV-negative controls (12%) or CIN3 cases (11%) had moved shown in Table 6. HPV16, by far the most prevalent single virus and were still untraced at the end of the study. It appears likely that type, has been analysed separately. Other viruses have been have women who move frequently and who do not re-register with a new been grouped according to their phylogeny based on nucleotide doctor are less likely to be in a permanent or long-term relationship. and amino acid sequence alignments of E6 sequences as published We would anticipate that any bias caused by this selection, there- by the Human Papillomavirus Database at Los Alamos National fore, would tend to weaken all the duration effects we found and so Laboratory (http//hpv-web.lanl.gov) (van Ranst et al, 1993). The our relative risk estimates are probably conservative. risk of CIN3 was far greater with HPV16 infection than with any Our analysis of CIN3 incidence in the whole Manchester cohort other type, including related genotypes. (Peto et al, in preparation) shows that CIN3 can develop quite rapidly in cytologically normal HPV carriers. Such women have a DISCUSSION risk of CIN3 being detected at the following smear of between 5 Our most remarkable finding is the striking difference between the and 10%. This observation, together with the findings here, indi- sexual risk factors that predict HPV infection and those that cates that the natural history of CIN3 often includes a long period predict CIN3 among infected women. A woman’s likelihood of of cytologically undetectable HPV infection. having a detectable HPV infection depends only on her number of The significant association between HPV infection and induced sexual partners and how recently she has acquired a new partner. abortion shown in Table 2 disappeared after adjustment for the The number of partners presumably determines the probability variables shown in Table 5, which reduced this OR from 2.35 that she has ever been infected. Most relationships would have (P<0.05) to 1.38 (not significant). Similar findings were previously ended many years earlier, and the fact that they still predict her risk reported by Karlsson et al. (1995). For spontaneous abortion, of a usually transient infection suggests that many such episodes however, the same adjustment increased the OR from 2.24 are recurrences of latent long-standing infection. In contrast, HPV (P<0.05) to 2.59 (P<0.01). This association between current HPV acquired from a new partner is likely to be an initial infection infection and previous spontaneous abortion supports the inference rather than a recurrence. The main risk factor for CIN3 among that many prevalent HPV infections are persistent or recurrent infected women is age at first intercourse, presumably because rather than newly acquired. duration of exposure is the main risk factor for neoplastic progres- Our results show no clear association of oral contraceptive use sion. The fact that number of partners does not increase the CIN3 with either HPV infection or disease. This is in contrast to a recent risk suggests that once a woman has been infected the risk is not study (Ylitalo et al, 1999) where current use was associated with a increased by reinfection. The CIN3 risk in infected women who highly significant four-fold increase in risk of CIN3. From Table 4 have not had a recent new partner is presumably high because it can be seen that HPV-infected women who used the pill for 8 diagnosis of CIN3 is often preceded by a period of persistent HPV years or more, and those whose first use was more than 8 years detectability which may well be an effect of subclinical neoplastic earlier, were at marginally increased although not significant risk progression rather than its cause. This risk factor raises a novel of CIN3. We have therefore analysed duration of use more than 8 epidemiological difficulty. We observed a marked protective effect years before diagnosis. The relative risk was 1.67 (1.03–2.72) in for HPV infection (OR 0.24) but an increased risk for CIN3 among ever users, but there was no significant trend with duration of use. British Journal of Cancer (2000) 83(11), 1565–1572 © 2000 Cancer Research Campaign Manchester case–control study of CIN31571 Breslow NE and Day NE (1980) Statistical Methods in Cancer Research. Vol 1 – This risk was reduced to 1.47 (0.89–2.43) when duration of latest The analysis of case-control studies. IARC Scientific Publications: Lyon relationship, which is correlated with long-term pill use, was Brinton LA (1992) Epidemiology of cervical cancer – overview. In The included in the model, and further reduced to 1.24 (0.72–2.15) epidemiology of human papillomavirus and cervical cancer. Munoz N, Bosch when adjusted for the other variables listed in Table 5. FX, Shah KV and Meheus A (eds), pp 3–23. International Agency for Research on Cancer: Lyon The evidence that smoking increases the risk of CIN3 and Evander M, Edlund K, Gustafsson A, Jonsson M, Karlsson R, Rylander E and cervical cancer, which has been accumulating over the last 25 Wadell G (1995) Human papillomavirus infection is transient in young women: years, has recently been reviewed by Szarewski and Cuzick a population-based cohort study. J Infect Dis 171: 1026–1030 (1998). They concluded that the increased risk seen in most studies Hildesheim A, Gravitt P, Schiffman MH, Kurman RJ, Barnes W, Jones S, Tchabo was reduced but not eliminated by adjustment for age at first inter- J-G, Brinton LA, Copeland C, Epp J and Manos MM (1993) Determinants of genital human papillomavirus infection in low-income women in Washington course and number of sexual partners, the residual risk remaining DC. Sex Transm Dis 20: 279–285 at or above two-fold in current smokers and showing a dose– Hinchliffe SA, van Velzen D, Korporaal H, Kok PL and Boon ME (1995) Transience response in many studies. The causal basis of the link, however, is of cervical HPV infection in sexually active young women with normal still controversial because of the marked correlation between cervicovaginal cytology. Br J Cancer 72: 943–945 Ho GYF, Bierman R, Beardsley L, Chang CJ and Burk RD (1998) Natural history of smoking and early sexual behaviour. In our study, for example, the cervicovaginal papillomavirus infection in young women. N Engl J Med 338: proportion of controls whose age at first sexual intercourse was 16 423–428 or less was 38% among women who had ever smoked and 19% IARC (1995) Monographs on the evaluation of carcinogenic risks to humans. among never smokers. The prevalence of HPV infection was also Vol 64 Human papillomaviruses. International Agency for Research on Cancer: increased among smokers in several studies, although the associa- Lyon Karlsson R, Jonsson M, Edlund K, Evander M, Gustavsson A, Boden E, Rylander E tion was reduced by adjustment for sexual variables (Ley et al, and Wadell G (1995) Lifetime number of partners as the only independent risk 1991; Bauer et al, 1993; Olsen et al, 1998). Szarewski and Cuzick factor for human papillomavirus infection: a population-based study. Sex (1998) noted that adjustment for HPV infection further reduced the Transm Dis 22: 119–127 effect of smoking on cervical neoplasia in some studies, raising Layde PM (1989) Smoking and cervical cancer: cause or coincidence? JAMA 261: 1631–1633 further doubts about the causal role of smoking (Morrison et al, Ley C, Bauer HM, Reingold A, Schiffman MH, Chambers JC, Tashiro CJ and 1991; Olsen et al, 1998). The independence of smoking and HPV Manos MM (1991) Determinants of genital human papillomavirus infection in infection in this study and the consistent and highly significant young women. J Natl Cancer Inst 83: 997–1003 dose-response for CIN3 compared with HPV-infected controls Manos MM, Ting Y, Wright DK, Lewis AJ, Broker TR and Wolinsky SM (1989) provide strong evidence that smoking acts synergistically with The use of polymerase chain reaction amplification for the detection of genital human papillomaviruses. Molecular Diagnostics of Human Cancer: Cancer HPV to cause cervical neoplasia. Cells 7: 209–214 Melkert PWJ, Hopman E, van den Brule AJC, Risse EKJ, van Diest PJ, Bleker OP, Helmerhorst T, Schipper MEI, Meijer CJLM and Walboomers JMM (1993) ACKNOWLEDGEMENTS Prevalence of HPV in cytomorphologically normal cervical smears, as determined by the polymerase chain reaction, is age-dependent. Int J Cancer Our thanks are due to all the clinic and laboratory staff who helped 53: 919–923 to construct the Manchester cohort, and to Heidi Bauer, Catherine Morrison EAB, Ho GYF, Vermund SH, Goldberg GL, Kadish AS, Kelley KF and Greer, Patti Gravitt and Cosette Wheeler for the provision of Burk RD (1991) Human papillomavirus infection and other risk factors for reagents and probes, and for their help in setting up our HPV labor- cervical neoplasia: a case-contol study. Int J Cancer 49: 6–13 atory. Most of all we thank the women, cases and controls, who so Olsen AO, Dillner J, Skrondal A and Magnus P (1998) Combined effect of smoking and human papillomavirus type 16 infection in cervical carcinogenesis. willingly agreed to participate and give interviews. Janet Wilson, Epidemiology 9: 346–349 together with Wendy Binns, performed the interviews, Michelle Phillips AN and Davey Smith G (1994) Cigarette smoking as a potential cause of Haywood and N Elanko ran the HPV lab, and Jane Hatch and cervical cancer: has confounding been controlled? Int J Epidemiol 23: 42–49 Doreen Lewis managed the data. Remmink AJ, Walboomers JMM, Helmerhorst TJM, Voorhorst FJ, Rozendaal L, Risse EKJ, Meijer CJLM and Kenemans P (1995) The presence of persistent The study was supported and funded by the Cancer Research high-risk HPV genotypes in dysplastic cervical lesions is associated with Campaign through project grants SP2285/0401 and SP2285/0501. progressive disease: natural history up to 36 months. Int J Cancer 61: 306–311 Schiffman MH (1992) Recent progress in defining the epidemiology of human papillomavirus infection and cervical neoplasia. J Natl Cancer Inst 84: REFERENCES 394–398 Szarewski A and Cuzick J (1998) Smoking and cervical neoplasia: a review of the Bauer HM, Ting Y, Greer CE, Chambers JC, Tashiro CJ, Chimera J, Reingold A and evidence. J Epidemiol Biostat 3: 229–256 Manos MM (1991) Genital human papillomavirus infection in female university students as determined by a PCR-based method. JAMA 265: van Ranst MA, Tachezy R, Delius H and Burk RD (1993) Taxonomy of the human 472–477 papillomaviruses. Papillomavirus Reports 4: 61–65 Bauer HM, Greer CE and Manos MM (1992) Determination of genital human Walboomers JMM, Jacobs MV, Manos MM, Bosch FX, Kummer JA, Shah KV, papillomavirus infection by consensus PCR amplification. In Diagnostic Snijders PJF, Peto J, Meijer CJLM and Munoz N (1999) Human papillomavirus molecular pathology: a practical approach. Herrington CS and McGee JOD is a necessary cause of invasive cervical cancer worldwide. J Pathol 189: (eds), pp 131–152. Oxford University Press: Oxford 12–19 Bauer HM, Hildesheim A, Schiffman MH, Glass AG, Rush BB, Scott DR, Cadell Wheeler CM, Parmenter CA, Hunt WC, Becker TM, Greer CE, Hildesheim A and DM, Kurman RJ and Manos MM (1993) Determinants of genital human Manos MM (1993) Determinants of genital human papillomavirus infection papillomavirus infection in low-risk women in Portland, Oregon. Sex Transm among cytologically normal women attending the University of New Mexico Dis 20: 274–278 Student Health Center. Sex Transm Dis 20: 286–289 Bosch FX, Manos MM, Munoz N, Sherman M, Jansen AM, Peto J, Schiffman MH, Ylitalo N, Sorensen P, Josefsson A, Frisch M, Sparen P, Ponten J, Moreno V, Kurman R and Shah KV. International Biological Study on Cervical Gyllensten U, Melbye M and Adami H-O (1999) Smoking and oral Cancer (IBSCC) Study Group (1995) Prevalence of human papillomavirus in contraceptives as risk factors for cervical carcinoma in situ. Int J Cancer 81: cervical cancer: a worldwide perspective. J Natl Cancer Inst 87: 796–802 357–365 © 2000 Cancer Research Campaign British Journal of Cancer (2000) 83(11), 1565–1572 1572 JM Deacon et al APPENDIX The Manchester UK cohort: clinical collaborators GP Practices: Drs D Bodey, S Hollingshead and T Rashid, Wilmslow Road, Fallowfield; Drs H Burgess, S Goodman and HC Sutherland, Mauldeth Road, Fallowfield; Drs K Checkland, M Jones and K Wells, Church Street, Marple, Stockport; Dr DN Riley, Robins Lane Medical Centre, Bramhall; Drs E Tierney, JCV Gillighan, JF Downie and AP Morris, Whitworth Medical Centre, Rochdale; Partners of the Northenden Group Practice, Palatine Road, Withington; Partners of the Robert Darbyshire Practice, Rusholme Health Centre Family planning clinics: Adswood Clinic, Stockport; Ancoats Hospital; Brinnington Clinic, Stockport; Cheadle Health Clinic, Stockport; Corporation Road Clinic, Eccles; Grasmere Street Health Centre, Leigh; Hazel Grove Clinic, Stockport; Heaton Norris Clinic, Stockport; Higher Broughton Health Centre, Salford; Hope Hospital, Salford; Lanceburn Health Centre, Salford; Langworthy Clinic, Salford; Little Hulton Clinic, Worsley; Liverpool Road Clinic, Hindley; Longsight Health Centre; Lower Broughton Clinic, Salford; Maple Clinic, Stockport; North Reddish Clinic, Stockport; Northern Hospital, Cheetham; Offerton Clinic Stockport; Offerton Green Clinic, Stockport; Partington Lane Clinic, Swinton; Romiley Health Centre, Stockport; Shaw Health Clinic, Stockport; St Mary’s Hospital; Stepping Hill Clinic, Stockport; The Palatine Centre, Palatine Road, Withington; Woodley Clinic, Stockport Screening clinics: Abbey Hey Clinic, Gorton; Alexandra Park Health Centre; Ancoats Community Clinic; Assheton Road Clinic, Newton Heath; Atherton Clinic, Wigan; Baguley Clinic; Beech Hill Health Centre, Wigan; Beswick Health Centre; Bevendon Square Clinic, Salford; Boothtown Clinic; Bramhall Clinic, Stockport; Bredbury Clinic, Stockport; Brookfield Clinics, Stockport; Brunswick Clinic; Burley House Clinic, Stockport; Central Drive Clinic, Crumpsall; Charlestown Health Centre, Blackley; Child Health Centre, Benchill; Clayton Health Centre; College Road Clinic, Leigh; Corporation Road Clinic, Eccles; Crumpsall Clinic; Derby Road Clinic, Golborne; Derbyshire House Clinic; Gorton Combined Clinic, West Gorton; Grasmere Street Health Centre, Leigh; Haig Road Clinic, Aspull; Harpurhey Health Centre; Hazel Grove Clinic, Stockport; Heaton Norris Clinic, Stockport; Hulme Clinic; Irlam Health Centre; Levenshulme Health Centre; Little Hulton Clinic, Worsley; Liverpool Road Health Centre, Hindley; Liverpool Street Clinic, Salford; Longshoot Lane Health Centre, Scholes; Lower Broughton Clinic, Salford; Monton Road Clinic, Eccles; Moss Side Health Centre; Newton Heath Health Centre; Nicholas Road Health Centre, Chorlton; North Reddish Clinic, Stockport; Offerton Clinic, Stockport; Ordsall Health Centre, Salford; Orrell Road Clinic, Wigan; Partington Lane Clinic, Swinton; Pemberton Clinic, Wigan; Plant Hill Clinic, Blackley; Platt Bridge Clinic, Wigan; Poplar Street Clinic, Tyldesley; Queens Road Clinic, Ashton-in-Makerfield; Romiley Clinic, Stockport; Smedley Street Clinic, Crumpsall; Standish Clinic, Wigan; Varley Street Clinic, Miles Platting; Walkden Clinic; Walmer Street Clinic, Rusholme; Wellwoman Clinic, Woodhouse Park; Wellwoman Clinic, Irlam; Wellwoman Clinic, Stockport; Wilmslow Road Clinic, Didsbury; Woodhouse Park Clinic, Wythenshawe British Journal of Cancer (2000) 83(11), 1565–1572 © 2000 Cancer Research Campaign

Journal

British Journal of CancerSpringer Journals

Published: Nov 14, 2000

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