Breast cancer is the most common cancer in Canadian women, with the exception of non-melanoma skin cancer. While it can also be found in men, male breast cancer is a very rare occurrence. Breast cancer starts in the cells of the mammary gland. Breast tissue covers a larger area than just the breast, extending up to the collarbone and from the armpit to the breastbone.
- In 2019 an estimated 26,900 Canadian women will be diagnosed with breast cancer and 5,000 will die of it.
- Breast cancer accounts for approximately 25% of new cases of cancer and 13% of all cancer deaths in Canadian women.
- 1 in 8 women are expected to develop breast cancer during her lifetime and 1 in 33 will die of it.
- Almost all breast cancers start in the glandular tissue of the breast and are known as adenocarcinomas. Cancer cells may start within the ducts (ductal carcinoma) or lobules (lobular carcinoma). Ductal carcinoma is the most common type of breast cancer, accounting for approximately 90% of all in situ breast carcinomas and 70% of all invasive breast carcinomas.
Please refer to the Breast Cancer in Canada infographic for more information.
There is no single cause of breast cancer but some factors that increase the risk of developing the disease include:
- Age: 83% of the cases of breast cancer occur in women over 50 years of age.
- Family history of breast cancer, especially in a mother, sister or daughter diagnosed before menopause, or if a mutation on the BRCA1 or BRCA2 genes is present.
- Previous breast disorders with biopsies showing abnormal cells.
- No full term pregnancies or having a full term first pregnancy after age 30.
- In post-menopausal women: obesity and physical inactivity.
- Beginning to menstruate at an early age.
- Later than average menopause.
- Taking hormone replacement therapy (estrogen plus progestin) for more than 5 years.
- Alcohol use
- What can I do to reduce my risk of cancer?
Managing Breast Cancer
Facts & Figures
Report a problem or mistake on this page
- Date modified: