Breast cancer
On this page
- About breast cancer
- Symptoms of breast cancer
- Treating and managing breast cancer
- Screening
- Risk factors
- What Canada's doing
About breast cancer
Breast cancer is when abnormal cells develop in the breast. 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).
Breast cancer is the most common cancer in females living in Canada, with the exception of non-melanoma skin cancer.
In Canada, 1 in 8 (13%) of females are expected to develop breast cancer during their lifetime and 1 in 36 (3%) will die of it. Breast cancer in males is rare, making up less than 1% of all breast cancers.
In 2024, an estimated 30,500 females in Canada were diagnosed with breast cancer and 5,500 were expected to die of it. This represents 25% of all new cases of cancer and 13% of all cancer deaths expected in 2024 among females living in Canada.
The probability of surviving breast cancer at least 5 years after diagnosis is about 89% for females in Canada.
Symptoms of breast cancer
Breast tissue covers a large area, extending from the armpit to the breastbone and up to the collarbone. Almost all breast cancers start in the glandular tissue of the breast that makes milk and carries it to the nipple. Common signs and symptoms include:
- pain in any area of the breast
- a new lump in the breast or armpit
- changes in the size or the shape of the breast
- dimpling or skin that looks like an orange peel
- a nipple that turns inward or appears flattened
- redness or flaky skin in the nipple area or breast
- nipple discharge other than breast milk (including blood)
It's important to know what's normal for your own breasts. You can then identify issues by noticing changes in the way your breasts look and feel.
Learn more:
Treating and managing breast cancer
Treatment plans depend on many factors. Our partners at the Canadian Cancer Society and the Canadian Breast Cancer Network have resources to help find what's best for you.
- Treatments for breast cancer
- Supportive care for breast cancer
- Breast cancer treatments and side effects
If you're supporting a friend or family member through their diagnosis, there are actions you can take to help.
How you can help someone coping with cancer
Screening
Breast screening is used to look for cancer in people who don't have any signs or symptoms. Screening aims to detect cancer at an earlier stage, when treatment is more likely to be successful. This differs from diagnostic testing, which is used when someone has signs or symptoms (for example, a lump).
Breast screening is important for protecting your health.
Find a breast cancer screening program in Canada (Canadian Cancer Society)
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Risk factors
There is no single cause of breast cancer, but some factors that may increase the risk of developing the disease include:
- age, as 83% of the cases of breast cancer occur in females over 50 years old
- family history of breast cancer, especially:
- in a mother, sister or daughter diagnosed before menopause
- if a mutation on the BRCA1 or BRCA2 genes is present
- these genes help repair damaged DNA, so mutations can increase the risk of developing breast cancer
- previous breast disorders with biopsies showing abnormal cells
- having dense breasts, which means there's a high proportion of fibrous or glandular tissue
- beginning to menstruate at an early age
- menopause occurring after age 55
- taking hormone replacement therapy (estrogen plus progestin) for more than 5 years
- having a full-term first pregnancy after the age of 35 or no full-term pregnancies
- being overweight or obese while postmenopausal
- drinking alcohol
Learn more:
What Canada's doing
A breast cancer diagnosis can profoundly affect individuals, families and communities. The Government of Canada is committed to addressing this by working with partners to advance breast screening, prevention and health promotion.
Through the Canadian Institutes of Health Research, investments have supported research to prevent, detect and treat breast cancer more effectively.
Through the Public Health Agency of Canada (PHAC), efforts are ongoing to raise awareness and ensure everyone has access to:
- the latest scientific evidence
- resources to safeguard their health and well-being
PHAC also plays an essential role in monitoring cancer data collected from national surveys and cancer registries. PHAC identifies trends in the rate of:
- new cancer cases (incidence)
- cancer deaths(mortality)
- survival after a cancer diagnosis
In collaboration with partners, PHAC makes significant contributions to the development and publication of reports on:
- cancer surveillance
- specific topics such as the cost of cancer and stage at diagnosis
These contributions help inform and evaluate public health programs, policies and initiatives nationwide.
Related links
- Canadian Cancer Statistics Dashboard
- Breast cancer (Canadian Cancer Society)
- Breast cancer statistics (Canadian Cancer Society)