Breast cancer in Canada

Breast cancer develops in the cells of the breast tissue. When these cells change or no longer behave normally, they may lead to benign tumours (non-cancerous). In some cases, the changes may cause malignant breast tumours (cancerous).

The data

• Breast cancer is the 3rd most common cancer in Canada
• 1 in 8 women will be diagnosed with breast cancer in her lifetime
• About 26,900 women will be diagnosed with breast cancer in 2019
• Breast cancer is the #1 cancer in women
• 83% occur in women aged 50+

Risk factors

• Age
• Family history
• BRCA gene mutation
• Reproductive status (e.g. late menopause)
• Hormone exposures (e.g. estrogen)
• Alcohol
• Obesity

Screening and detection

• 70% of breast cancer cases are diagnosed early in their development, at stage I and II*
• 88% of Canadian women diagnosed with breast cancer survive 5 or more years

Routine breast cancer screening with mammography every 2 to 3 years is recommended for women aged 50 to 74.

Screening guidelines are available from the Canadian task Force on Preventive Health Care.