Understanding Breast Cancer Risks

Understanding Breast Cancer Risks

By Janice Harvey, RPh, CDE

Breast cancer is the most common type of cancer. When the numbers of breast, lung, prostate and colorectal cancers are combined, they make up almost half of all cancer diagnoses.

Every year, almost 28,000 Canadians are diagnosed with breast cancer. In BC, in 2020 (the last year for which we have statistics), 750 people were diagnosed with breast cancer. All of those were female. (1) Breast cancer in men accounts for less than 1% of all breast cancers. (2)

What are the risk factors?

Most breast cancers occur in women, since their breast cells are exposed to the female hormones estrogen and progesterone, which have been shown to encourage cancer growth. Risk increases with age. Over 80% of new breast cancers diagnosed each year in BC are in women age 50 or older. Breast cancer may even develop in individuals who don’t have any of the risk factors.

Some examples of factors that have been shown to increase risk include a personal or family history of breast and other cancers, dense breast tissue, and reproductive history (e.g., early menstruation, late menopause, and late pregnancy or no pregnancies) that increases the length of time that breast tissue has been exposed to estrogen. Please visit the Canadian Cancer Agency website for more information about these and other risk factors. (2)

Women are often concerned about the increased risk for breast cancer when taking combined hormone replacement therapy (estrogen plus progestin) for menopausal symptoms. Indeed, the risk is greater when taking oral HRT medications for 5 years or longer, and researchers believe that the risks of long-term use outweigh the benefits. Risks can be minimized by using topical products that contain estrogen alone (e.g., vaginal estrogen).

Despite social media claims to the contrary, there is no connection between antiperspirants, deodorants, abortion, breast implants, or bras and breast cancer. For example, breast implants can make it more difficult to visualize cancer on a mammogram, but they do not increase the risk of developing breast cancer. (2)

Can the risk be reduced?

While you can’t change your genetics, there are lifestyle changes that you can make to improve your overall health and reduce your risk of develop breast cancer:

  • Reduce alcohol intake – Alcohol is thought to cause higher levels of estrogen. It may also lower levels of some nutrients that protect against cell damage, such as folate, vitamin A and vitamin C.
  • Maintain a normal body weight – Fat tissue produces a small amount of estrogen, thus increasing breast tissue exposure to estrogen even in post-menopausal women.
  • Increase physical activity – Women of all age groups who are inactive have an increased risk for breast cancer, though the reasons for this have not yet been determined.

How do you do a breast self-examination?

All women, regardless of age or risk factors, should be breast aware. This means knowing how your breasts normally look and feel so you can tell if there are changes. A 2008 study of nearly 400,000 women found that self-exams were not effective in finding cancer early enough to change survival rates. However, some agencies still recommend self-exams in combination with regular screening mammograms to increase the odds of early detection.

The steps for doing a breast self-exam can be found here: https://www.breastcancer.org/screening-testing/breast-self-exam-bse. (3) Some signs to watch for include: a lump in the breast, nipple pain, an inverted nipple, nipple discharge, sores on the nipple and areola, or enlarged lymph nodes under the arm. Advise your doctor or nurse practitioner if you notice any breast changes.

Should you get a mammogram?

In Canada, the Canadian Task Force for Preventive Health Care has developed national guidelines (4) for breast cancer screening. These guidelines recommend:

  • Women aged 50–74 should schedule a mammogram every 2 to 3 years.
  • In women aged 40 to 49, routine mammograms are not recommended, since the risk of having breast cancer is lower and the chance of a false positive test result is higher in this age group. Dense breasts are more common amongst younger women and the fatty tissue may be mistaken as cancerous tissue, resulting in unnecessary additional testing and biopsies.
  • For women older than 75 years, it is not clear if the benefits of regular screening outweigh the risks of regular x-rays.

Talk to your doctor about a personal plan for testing if you think you might have a higher-than-average risk for breast cancer.


In the Comox Valley, screening mammogram appointments are held at North Island Hospital. You can book your appointment by calling the hospital directly at 250-331-5949, or call the Screening Programs Client Services Centre at 1-800-663-9203. You do not need a doctor’s referral. Visit the BC Cancer website for detailed information on booking a mammogram appointment and what to expect: http://www.bccancer.bc.ca/screening/breast/get-a-mammogram.


  1. https://bccandataanalytics.shinyapps.io/BCSummary/
  2. https://cancer.ca/en/cancer-information/cancer-types/breast/what-is-breast-cancer
  3. https://www.breastcancer.org/
  4. https://canadiantaskforce.ca/tools-resources/breast-cancer-2/breast-cancer-patient-faq/
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