A population-based analysis of breast cancer incidence and survival by subtype in Ontario women

  • S. J. Seung HOPE Research Centre, Sunnybrook Research Institute
  • A. N. Traore
  • B. Pourmirza Hoffmann–La Roche Limited
  • K. E. Fathers Hoffmann–La Roche Limited
  • M. Coombes Hoffmann–La Roche Limited
  • K. J. Jerzak Odette Cancer Centre, Sunnybrook Health Sciences Centre
Keywords: Breast cancer, subtype, incidence, overall survival, epidemiology


Background:  Breast cancer (BC) is the most frequently diagnosed type of cancer among women in Canada. BC is defined by different molecular subtypes; by the expression of estrogen receptors (ER), progesterone receptors (PR) and the human epidermal growth factor receptor-2 (HER2). Currently, Canada has no national cancer registry with epidemiology data by subtype. Thus, we conducted a study to determine the incidence, survival and clinicopathological characteristics of BC subtypes (triple negative breast cancer (TNBC), HER2+, and hormone receptor positive (HR+/HER2-) in Canadian women newly diagnosed with BC. Methods: Female patients diagnosed between April 1, 2012 and March 31, 2016 (fiscal 2012-2015) were identified in the Ontario Cancer Registry and individual patient data were linked to data in provincial health administrative databases. Descriptive statistics and Kaplan-Meier curves were generated. Results: In this cohort, 3,277 (9.5%) patients had TNBC, 4,902 (14.3%) had HER2+, and 22,247 (64.8%) had HR+ breast cancer. The annual incidence was 15 per 100,000 for the TNBC group, 21–23 per 100,000 for the HER2+ group, and 97–105 per 100,000 for the HR+ group. The lowest median overall survival (mOS) of only 8.9 months was observed among patients with clinical stage IV TNBC; in comparison, the median OS was 37.3 months and 35.2 months among women with HER2+ and HR+/HER2- metastatic BC, respectively. Conclusions: This study, the most recent and largest administrative database analysis of a Canadian population to date, reveals a subtype distribution consistent with previously reported data along with comparable annual incidence and overall survival patterns.

Author Biographies

B. Pourmirza, Hoffmann–La Roche Limited

Department of Medical Affairs

K. E. Fathers, Hoffmann–La Roche Limited

Department of Medical Affairs

M. Coombes, Hoffmann–La Roche Limited

Market Access and Pricing Department

How to Cite
Seung, S. J., Traore, A. N., Pourmirza, B., Fathers, K. E., Coombes, M., & Jerzak, K. J. (2019). A population-based analysis of breast cancer incidence and survival by subtype in Ontario women. Current Oncology, 27(2). https://doi.org/10.3747/co.27.5769
Translational Research