Screening for Breast Cancer

Breast cancer was expected to be the most common cancer diagnosed in Ontario women in 2018. Screening mammography can find breast cancers when they are small, less likely to have spread and more likely to be treated successfully. Your age and family medical history help determine when you should get screened:

• If you are age 50 to 74, the Ontario Breast Screening Program (OBSP) recommends that most people in your age group be screened every 2 years with mammography. Find your nearest OBSP site by calling 1-800-668-9304 or visiting Ontario Breast Screening Program locations.
• If you are age 30 to 69 and meet any of the following requirements, talk to your doctor or nurse practitioner about referral to the High Risk Ontario Breast Screening Program:
  
  • You are known to have a gene mutation that increases your risk for breast cancer (e.g., BRCA1, BRCA2, TP53, PTEN, CDH1)
  • You are a first-degree relative (parent, sibling or child) of someone who has a gene mutation that increases their risk for breast cancer (e.g., BRCA1, BRCA2, TP53, PTEN, CDH1)
  • You have a personal or family history of breast or ovarian cancer
  • You have had radiation therapy to the chest to treat another cancer or condition (e.g., Hodgkin lymphoma) before age 30 and at least 8 years ago

For every 200 women screened in the Ontario Breast Screening Program, about 18 are referred for further tests and 1 will have breast cancer.

Mammography remains the best screening test for most people. A screening mammogram takes an X-ray picture of the breast and can find breast cancers when they are small, less likely to have spread and more likely to be treated successfully.

Mammograms are considered safe and use a low dose of radiation. The benefits of screening and finding cancer early are more important than any potential harm from the X-ray. Most people will have normal mammogram results.

How Effective Are Screening Mammograms?

Mammograms are the best way to find breast cancer early. But they are not perfect tests. Mammograms may miss some breast cancers. Also, some cancers develop in the time between screens. However, many studies have shown that regular mammograms reduce the risk of dying from breast cancer. 

Some breast cancers that are diagnosed through screening may never cause symptoms in a person during their lifetime (i.e., over-diagnosis). Therefore, some people may have surgery or treatment for a breast cancer that would not have become life threatening. 

Not all cancers found at screening can be treated successfully.

To learn more about what happens during a mammogram and how to get ready for a mammogram, see the Mammogram FAQs.

People ages 50 to 74 can call the nearest Ontario Breast Screening Program location to make an appointment (a doctor or nurse practitioner referral is not needed).

People in the North West and Hamilton Niagara Haldimand Brant regions may be eligible for screening in one of our mobile screening coaches.

If you think you may be at high risk for breast cancer, talk to your doctor or nurse practitioner about a referral to the High Risk Ontario Breast Screening Program based on family and/or medical history.

The Ontario Breast Screening Program (OBSP) is a province-wide organized screening program that aims to reduce breast cancer mortality through regular screening. The program provides screening for most people ages 50 to 74, and for people ages 30 to 69 who are confirmed to be at high risk of developing breast cancer.

The High Risk OBSP sites help people who may be at high risk of getting breast cancer to undergo genetic assessment. To learn about the eligibility requirements for the High Risk OBSP, see Breast Cancer Screening for Women at High Risk. For people who have been confirmed to be at high risk of getting breast cancer, High Risk OBSP sites offer yearly screening mammograms and breast magnetic resonance imaging (MRI) (or screening breast ultrasound if MRI is not medically appropriate). For people with abnormal screening results, the High Risk OBSP sites coordinate follow-up breast assessments (i.e., any additional tests they need).

Ontario Health (Cancer Care Ontario) sends eligible people for the Ontario Breast Screening Program letters inviting them to get screened, informing them of their results, and reminding them when it is time to return for screening. 

Letters People May Receive

• Correspondence privacy notice
• Invitation letter
• Invitation reminder
• Recall letter (2 years)
• Recall reminder
• Normal result letter (1 year recall)
• Normal result letter (2 year recall)
• Normal result letter (no recall)

A sample of each letter type is available in the Letters to the Public area.   

Breast Density Information

• Breast Density Information for Ontario Breast Screening Program Participants

Ontario Breast Screening Brochure

The brochure called “Breast Cancer Screening – it’s never this obvious” provides information on when it is the right time for you to start screening.

Breast Cancer Screening Brochure

Public Health Agency of Canada Brochures

• Breast Cancer and Your Risk

Helpful Websites

• My CancerIQ
• Canadian Cancer Society