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Screening for breast cancer

Whatever your age, you should know what is normal for your breasts and tell your doctor if you notice any changes. Once you reach a certain age, you can also go for screening mammography, a low-dose x-ray. Mammography is the most reliable method of finding breast cancer.

  • Our recommendation

    If you are 40 to 49: Talk to your doctor about your risk of breast cancer, along with the benefits and risks of mammography.

    If you are 50 to 69: Have a mammogram every 2 years.

    If you are 70 or older: Talk to your doctor about how often you should have a mammogram.

    Research has shown that women who have mammograms regularly are less likely to have a false positive (when the test results suggest cancer when none is present). We also know that if you do have cancer, it is more likely to be detected when you have mammograms regularly.

    Your doctor may also do a physical examination of your breasts (a clinical breast examination) to check for signs of cancer.

  • What happens when you have a mammogram?

    Screening mammograms are done in a clinic or screening centre.

    Mammography pictures (mammograms) show detailed images and views of the breast taken from different angles. When you have a mammogram, the breast is placed between two plastic plates. The plates are then pressed together to flatten the breast. This may be uncomfortable, but it lasts only a few seconds. Compressing the breast tissue helps make the images clearer while using as little radiation as possible.

    A screening mammogram is done to screen women with no signs of breast cancer, while a diagnostic mammogram helps diagnose women who have signs of breast cancer. If you have any questions about what type of test you’re having and why, ask your doctor.

  • Benefits and risks of mammography

    Almost every test or procedure has benefits and risks. It’s important to be aware of them so that you can make an informed decision that’s right for you. No screening test is 100% accurate, but the scientific evidence tells us that having mammograms leads to a decrease in death rates in women with cancer.


    • Better survival rates – In most cases, the earlier a cancer is detected, the better your chance of survival. Research has shown that women who have regular mammograms are more likely to survive breast cancer.
    • Better quality of life – Early detection may also mean less treatment and less time spent recovering. Research has proven that breast cancers detected in women who have regular mammograms are on average smaller and more treatable.


    • False positive results – When test results suggest cancer even though cancer is not present. False positives can result in anxiety, stress and possibly painful and unnecessary tests to rule out cancer (that is, to make sure you don’t have cancer when the screening test has suggested you might). For example, research has shown that screening for breast cancer in younger women may lead to many more false positives. There is still uncertainty whether regular mammograms in women under the age of 50 saves lives.
    • False negative results – When cancer is not detected by the test even though it is present. False negative results can cause you or your physician to ignore other symptoms that suggest the presence of cancer, causing a delay in diagnosis and treatment.
    • Over-diagnosis – Certain cancers may never cause any symptoms or decrease life expectancy or quality for life. However, research indicates that most breast cancers are harmful, and that breast cancer should be detected and treated as early as possible.
    • Increased exposure to harmful procedures, for example, very low doses of radiation from x-ray tests.
  • Breast screening programs

    Breast screening programs vary between provinces. All provinces have breast cancer screening programs for women age 50 to 69. You can make an appointment at a screening centre without a doctor’s referral.

    For women aged 40 to 49, the situation is not as straightforward. Depending on your provincial program, you may be able to make an appointment without a referral or you may need your doctor or nurse practitioner to refer you to the program (following a discussion about the benefits and risks of screening). It may be that your provincial screening program simply does not accept women aged 40 to 49. In that case, you may need to talk to your doctor about the best way to have a mammogram.



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