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

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 ¼ 287) to a frequencymatched random sample of non-FN women (n ¼ 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 ¼ 3.10, 95% CI ¼ 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 ¼ 4.65, 95% CI ¼ 1.39-15.53) and was more than five times greater for women with diabetes (HR ¼ 5.49, 95% CI ¼ 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. Ó2011 AACR.

Research in cancer care disparities in countries with universal healthcare: mapping the field and its conceptual contours

“…In part, this is a consequence of how studies are indexed. We consider this point more fully in the discussion, but for now it bears noting that one Canadian study [117] that included attention to differences in receipt of treatment between First Nations and non-First Nations women was not included in this review as it was not indexed nor did it use text word terms for 'health services accessibility' or 'healthcare disparities' (the emphasis was on differences rather than disparities).…”

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