Abstract A44: The prevalence of prognostic and treatment features for breast cancer survival: Are they different for First Nations women compared to other women in Ontario, Canada?

Background: There is growing literature in the United States proposing that the distribution of some prognostic features for cancer may vary by ethnic/racial status. Among Canadian cancer registries, data on prognostic features, as well as treatment, ethnicity, socioeconomic status, are not routinely collected. To determine these characteristics, data from medical charts of the cancer patient is abstracted. Previous work in Ontario, Canada has demonstrated that survival after a breast cancer diagnosis is poorer among First Nations women compared to other Ontario women. The purpose of this study is to identify the distribution of prognostic features and treatment received among First Nations and non-First Nations women diagnosed with breast cancer from 1995 to 2004 in Ontario.

Study Design: This study employed a case-case design using the cohort of First Nations people in Ontario to identify 297 women diagnosed with invasive breast cancer between 1995 and 2004. Concurrently, a random sample of 694 non-First Nations women were selected through the population-based cancer registry at Cancer Care Ontario and matched 2 to 1 on five-year date of diagnosis, age at diagnosis (15–54 vs. 55+), and Integrated Cancer Program (ICP) first attended. Data on stage at diagnosis, treatment received, risk factors and co-morbid conditions was collected from medical charts at the provincial ICP.

Analysis: Univariate analyses were calculated by First Nations status.

Results: A similar proportion of First Nations women are screened with mammography; stage at diagnosis is later for First Nations women (71% are diagnosed at stage II or higher compared to 55% among other Ontario women); proportions of women receiving chemo/hormonal therapy are similar; proportion of women undergoing biopsies and surgeries are similar, however the distribution of each procedure is different (for instance, modified radical mastectomies are 14% higher among First Nations women); and proportion of women having radiotherapy are lower for First Nations women.

Conclusions: It is important to identify the prognosis and treatment factors that influence breast cancer survival in First Nations women. These preliminary findings will be further explored and controlled for variables such as socioeconomic status and other tumor characteristics. Once better understood, actions can be taken to improve the prognosis and treatment of First Nations women with breast cancer.