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Stage at Diagnosis and Comorbidity Influence Breast Cancer Survival in First Nations Women in Ontario, Canada

Stage at Diagnosis and Comorbidity Influence Breast Cancer Survival in First Nations Women in... Background: Indigenous populations in Canada and abroad have poorer survival after a breast cancer diagnosis compared with their geographic counterparts; however, the influence of many demographic, personal, tumor, and treatment factors has not been examined to describe this disparity according to stage at diagnosis. Methods: A case–case design was employed to compare First Nations (FN) women ( n = 287) to a frequency-matched random sample of non-FN women ( n = 671) diagnosed with breast cancer within the Ontario Cancer Registry. Women were matched on period of diagnosis (1995–1999 and 2000–2004), age at diagnosis (<50 vs. ≥50), and Regional Cancer Centre (RCC). Stage and other factors were collected from medical charts at the RCCs. Survival was compared using an adjusted Cox proportional hazards model and stratified by stage at diagnosis (I, II, and III–IV). Determinants of survival in FN women stratified by stage at diagnosis were also modeled. Results: Survival was more than three times poorer for FN women diagnosed at stage I than for non-FN women (HR = 3.10, 95% CI = 1.39–6.88). The risk of death after a stage I breast cancer diagnosis was about five times higher among FN women with a comorbidity other than diabetes (HR = 4.65, 95% CI = 1.39–15.53) and was more than five times greater for women with diabetes (HR = 5.49, 95% CI = 1.69–17.90) than for those without a comorbidity. Conclusions: Having a preexisting comorbidity was the most important factor in explaining the observed survival disparity among FN women. Impact: Improving the general health status of FN women could increase their survival after an early-stage breast cancer diagnosis. Cancer Epidemiol Biomarkers Prev; 20(10); 2160–7. ©2011 AACR . This article is featured in Highlights of This Issue, p. 1991 Received May 20, 2011. Revision received July 13, 2011. Accepted July 25, 2011. ©2011 American Association for Cancer Research. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Cancer Epidemiology, Biomarkers & Prevention American Association of Cancer Research

Stage at Diagnosis and Comorbidity Influence Breast Cancer Survival in First Nations Women in Ontario, Canada

Stage at Diagnosis and Comorbidity Influence Breast Cancer Survival in First Nations Women in Ontario, Canada

Cancer Epidemiology, Biomarkers & Prevention , Volume 20 (10): 2160 – Oct 1, 2011

Abstract

Background: Indigenous populations in Canada and abroad have poorer survival after a breast cancer diagnosis compared with their geographic counterparts; however, the influence of many demographic, personal, tumor, and treatment factors has not been examined to describe this disparity according to stage at diagnosis. Methods: A case–case design was employed to compare First Nations (FN) women ( n = 287) to a frequency-matched random sample of non-FN women ( n = 671) diagnosed with breast cancer within the Ontario Cancer Registry. Women were matched on period of diagnosis (1995–1999 and 2000–2004), age at diagnosis (<50 vs. ≥50), and Regional Cancer Centre (RCC). Stage and other factors were collected from medical charts at the RCCs. Survival was compared using an adjusted Cox proportional hazards model and stratified by stage at diagnosis (I, II, and III–IV). Determinants of survival in FN women stratified by stage at diagnosis were also modeled. Results: Survival was more than three times poorer for FN women diagnosed at stage I than for non-FN women (HR = 3.10, 95% CI = 1.39–6.88). The risk of death after a stage I breast cancer diagnosis was about five times higher among FN women with a comorbidity other than diabetes (HR = 4.65, 95% CI = 1.39–15.53) and was more than five times greater for women with diabetes (HR = 5.49, 95% CI = 1.69–17.90) than for those without a comorbidity. Conclusions: Having a preexisting comorbidity was the most important factor in explaining the observed survival disparity among FN women. Impact: Improving the general health status of FN women could increase their survival after an early-stage breast cancer diagnosis. Cancer Epidemiol Biomarkers Prev; 20(10); 2160–7. ©2011 AACR . This article is featured in Highlights of This Issue, p. 1991 Received May 20, 2011. Revision received July 13, 2011. Accepted July 25, 2011. ©2011 American Association for Cancer Research.

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Publisher
American Association of Cancer Research
Copyright
Copyright © 2012 American Association for Cancer Research
ISSN
1078-0432
eISSN
1538-7755
DOI
10.1158/1055-9965.EPI-11-0459
pmid
21803843
Publisher site
See Article on Publisher Site

Abstract

Background: Indigenous populations in Canada and abroad have poorer survival after a breast cancer diagnosis compared with their geographic counterparts; however, the influence of many demographic, personal, tumor, and treatment factors has not been examined to describe this disparity according to stage at diagnosis. Methods: A case–case design was employed to compare First Nations (FN) women ( n = 287) to a frequency-matched random sample of non-FN women ( n = 671) diagnosed with breast cancer within the Ontario Cancer Registry. Women were matched on period of diagnosis (1995–1999 and 2000–2004), age at diagnosis (<50 vs. ≥50), and Regional Cancer Centre (RCC). Stage and other factors were collected from medical charts at the RCCs. Survival was compared using an adjusted Cox proportional hazards model and stratified by stage at diagnosis (I, II, and III–IV). Determinants of survival in FN women stratified by stage at diagnosis were also modeled. Results: Survival was more than three times poorer for FN women diagnosed at stage I than for non-FN women (HR = 3.10, 95% CI = 1.39–6.88). The risk of death after a stage I breast cancer diagnosis was about five times higher among FN women with a comorbidity other than diabetes (HR = 4.65, 95% CI = 1.39–15.53) and was more than five times greater for women with diabetes (HR = 5.49, 95% CI = 1.69–17.90) than for those without a comorbidity. Conclusions: Having a preexisting comorbidity was the most important factor in explaining the observed survival disparity among FN women. Impact: Improving the general health status of FN women could increase their survival after an early-stage breast cancer diagnosis. Cancer Epidemiol Biomarkers Prev; 20(10); 2160–7. ©2011 AACR . This article is featured in Highlights of This Issue, p. 1991 Received May 20, 2011. Revision received July 13, 2011. Accepted July 25, 2011. ©2011 American Association for Cancer Research.

Journal

Cancer Epidemiology, Biomarkers & PreventionAmerican Association of Cancer Research

Published: Oct 1, 2011

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