Reducing Your Risk of Breast Cancer: Prevention and Screening

Breast cancer is the most common cancer in women, with the exception of non-melanoma skin cancers. The Canadian Cancer Society estimated that 25% of all new cancer cases in women in 2019 would be caused by breast cancer. Men can also get breast cancer, but it’s rare. However, the annual incidence of breast cancer in men appears to be rising; one report suggests that incidence has increased 26 percent over the past 25 years.

While there are a number of ways to lower your risk of developing breast cancer, there is no way to prevent it. That’s why early detection to improve breast cancer outcome and survival is so important and remains the cornerstone of breast cancer control, according to the World Health Organization (WHO).

To date, mammography screening – a low-dose x-ray – has proved to be the most effective breast cancer screening method available. Mammograms help find cancer in its earliest stages when there is a better chance for successful treatment.

Breast cancer risks

There is no single cause of breast cancer but researchers have identified hormonal, lifestyle and environmental factors that may increase your risk of developing the disease. However, it’s not clear why some people with no risk factors develop cancer, yet other people with risk factors do not. Breast cancer is likely caused by a complex interaction of your genetic makeup and your environment.

Risk factors include:

  • Age: 83% of breast cancer cases occur in women over 50 years old; men tend to be approximately 5 to 10 years older than women at the time of diagnosis
  • Family history: A family history of breast cancer, especially in a mother, sister or daughter diagnosed before menopause, or the presence of a mutation on the BRCA1 or BRCA2 genes. (only 5%-10% of women who develop breast cancer have a genetic risk); Approximately 15 to 20 percent of men with breast cancer have a family history of the disease compared with only 7 percent of the general male population
  • Previous breast disorders: with biopsies showing abnormal cells
  • Dense breasts: Dense breasts have more connective tissue, glands and milk ducts than fatty tissue
  • No full-term pregnancies: or having a full-term first pregnancy after age 30
  • Obesity and physical inactivity
  • Beginning to menstruate before age 12
  • Menopause after age 55
  • Taking hormone replacement therapy (estrogen plus progestin) for more than 5 years
  • Alcohol use

How to reduce your risk of breast cancer

You can’t control some risk factors like a family history of breast cancer but there are lifestyle changes and other steps you can take that can lower your risk of breast cancer. Up to 42% of breast cancers are linked to lifestyle factors while 5%-10% have a genetic cause. To lower your risk:

  • Limit the amount of alcohol you drink. Even small amounts can raise your risk. Compared with no drinks a day, each daily alcoholic drink raises your risk by almost 10%.
  • Maintain a healthy weight. Small changes in your diet and physical activity may help you become healthier. Even losing a small amount of weight can help lower your risk.
  • Stay active. Physical activity, including daily activities such as gardening, housework and walking, can improve your health, well-being and quality of life and lower your risk of cancer.
  • Talk to your doctor about the benefits and risks of birth control pills and hormone replacement therapy (HRT). You may have a higher risk of breast cancer if you have taken birth control pills. Your risk decreases when you stop taking them. Taking HRT for a long time, especially with both estrogen and progesterone, may raise your risk of breast cancer. Your risk quickly falls after you stop taking it. Talk to your doctor or nurse practitioner before making any medication changes.
  • Consider breastfeeding if possible. Breastfeeding, particularly for one year or more over the course of a lifetime, may lower your breast cancer risk.
  • Talk to your doctor to see if you are at high risk of breast cancer. You may be referred for high risk screening or a genetic assessment if you: have a personal or family history of breast or ovarian cancer; are diagnosed with breast cancer before age 35; have a strong family history of breast, ovarian or related cancers; are a first-degree relative (parent, brother, sister or child) of someone who has a gene mutation that increases their risk for breast cancer (e.g., BRCA1, BRCA2, TP53, PTEN, CDH1); have a family history of male breast cancer; or, are of Ashkenazi Jewish descent.
  • Be breast self-aware. Know how your breasts normally look and feel so if they change, you will know and can contact your doctor right away. Watch for: breast lumps or swelling anywhere in the breast or underarm area; nipple discharge (clear or bloody); a change in how the nipples look or feel; a change in how the breast skin looks or feels; or a change in breast size, shape or symmetry.

Research suggests that other factors such as smoking, being exposed to chemicals that can cause cancer, and changes in other hormones due to night shift work may also increase breast cancer risk but more study is needed to clarify the role of these factors for breast cancer.

When to have a mammogram

Cancer screening is testing done on people who may be at risk of getting cancer, but who have no symptoms and generally feel fine.

Screening mammography – a low-dose x-ray – is used to detect early stages of breast cancer, often before a lump can be physically felt. A mammogram can find breast cancers when they are small, less likely to have spread and more likely to be treated successfully.

No screening test is 100% accurate, but scientific evidence shows that having regular mammograms lowers the risk of dying from breast cancer. You should be aware of the benefits and limitations of screening mammography based on your age and risk factors to help decide if it is right for you. Talk with your doctor to help make your decision.

If you are at AVERAGE RISK for breast cancer

Canadian guidelines for breast screening for women at average risk for breast cancer, developed by The Canadian Task Force on Preventive Health Care, recommend:

  • Women under 40:No screening. If you notice any breast changes, consult a doctor right away.
  • Women 40-49:No screening. A review of the evidence shows there is no mortality benefit to screening for women of average risk in this age category. However, you can talk to your doctor about your risk for breast cancer, along with the benefits and limitations of having a mammogram. Research on regular mammograms for women in their 40s is still ongoing.
  • Women 50-74:Routine screening mammography every 2 to 3 years. (61% of cases of breast cancer occur in women ages 50-74) The Canadian Cancer Society recommends a mammogram for this age group every 2 years.
  • Age 75 or older:No recommendations were made for this age group. Talk to your doctor about your risk factors and how often you need a mammogram.

If you are at HIGH RISK for breast cancer

For women at high risk of developing breast cancer, start breast screening at age 30.​ The Ontario Breast Screening Program (OBSP) recommends that women between the ages of 30 and 69 who are at high risk for breast cancer get screened with annual mammography and breast magnetic resonance imaging (MRI). If MRI is not medically appropriate, a screening breast ultrasound may be given instead.

Whether you are at average or high risk for breast cancer, it is important to speak with your doctor or nurse practitioner about the benefits and limitations of breast cancer screening.

For more information or to speak to one of our Nurse Case Managers, contact us at 1-866-883-5956.


BC Cancer

Cancer Care Ontario

Canadian Cancer Society

Canadian Cancer Society: Screening

Canadian Cancer Society: Statistics

Centers for Disease Control and Prevention

Government of Canada

Mayo Clinic

Rethink Breast Cancer

The Canadian Task Force on Preventive Health Care

UHN Princess Margaret Cancer Centre


World Health Organization