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Breast Cancer

Screening mammography remains important for the early detection of breast cancer and woman aged 50-74 should participate in regular screening every two years.

The Screening Mammography Program of BC has seen a 25 percent reduction in deaths from breast cancer among women in the province who have regular screening mammograms.

The effectiveness of screening mammography has been well established by several large clinical trials across the world. These trials have found a relative risk reduction of breast cancer deaths of between 15-25% for women aged 50-69. Of eight randomized control trials for screening mammography, seven showed that screening mammography is beneficial.

In February 2014, the British Medical Journal published 25-year follow-up results from the Canadian National Breast Screening Study—the only randomized control trial suggesting that annual screening in women age 40-59 does not reduce breast cancer mortality beyond that of physical examination (for the 50-59 year olds) or usual care (for 40-49 year olds). The BC Cancer Agency does not agree with the findings in this study, and other credible evidence does not correlate with the findings.


Recent changes were made to BC’s policy on breast cancer screening based on the results of an evidence review:

Women with a first degree relative (mother, daughter, sister) with breast cancer:

  • If you are age 40 to 74, it is recommended that you get a mammogram every year.
    • Women with a family history of breast cancer are almost two times more likely to develop breast cancer.

Average risk, no first degree relative with breast cancer:

  • Women age 40-49 are encouraged to have a discussion about the limitations and benefits of screening with their primary care provider.
    • In consideration of the evidence regarding risk and benefits in this age group, BC’s policy also recommends that for average risk women in this age group be screening every two years.
    • BC’s policy for women in their 40’s took into account recommendations by the Canadian Task Force on Preventive Health Care regarding breast cancer screening – weighing the limitations and the benefits for women in their forties, as well as other research.
  • Women age 50-74 should participate in regular screening every two years.
  • If you are age 75+ you are encouraged to talk to your doctor about the benefits and limitations of mammography. If screening mammography is chosen, it is available every two to three years. A doctor’s referral is not needed but is recommended.

There is no current policy regarding the reporting of dense breast tissue in Canada. Further studies are required to determine if additional screening tests are appropriate for women with increased breast density, including an understanding of the advantages and disadvantages of additional testing.

At present, in BC and in Canada, a breast density assessment from a mammogram is subjective; therefore the accuracy of determining breast density from a mammogram at this time would be questionable and could lead to a lot of unnecessary concern and follow-up.

No screening test is perfect, and mammography is no exception. Factors like age or breast density can influence the look of breast tissue on a mammogram, making cancers more or less difficult to recognize. But many cancers are found on mammograms even if dense breast tissue is present.


Mammograms are the screening test proven to reduce breast cancer deaths. Being “breast aware” is always an important component of breast health and any breast changes should be discussed with your health care provider right away, even if you have had a recent mammogram.

The BC Cancer Agency is dedicated to improving the detection of cancer, and the Screening Mammography Program of BC is no exception. We continue to assess the latest evidence and tools available to better detect, prevent and treat cancer.

More information about screening can be found at:

SOURCE: Breast Cancer ( )
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