New breast cancer screening guidelines put women at risk

Breast cancer is the second leading cause of death from cancer in Canadian women. On any given day, 72 Canadian women are diagnosed with breast cancer and 14 Canadian women will die from it. Over the course of a lifetime, one in eight Canadian women will develop breast cancer and one in 31 will lose their life to it. In December 2018, the Canadian Task Force on Preventive Health Care (CTF) issued new guidelines on breast cancer screening for women of average risk. These recommendations are used by 36,000 family doctors in their interactions with nine million women aged 40 to 74. Contrary to established practice, the new guidelines advise against mammography for women aged 40 to 49 and recommend that women aged 50 to 74 only have mammograms every two to three years. In addition, they recommend against performing clinical examinations and self-examinations to screen for breast cancer. Experts in breast cancer screening and patient advocates have responded to these new guidelines with tremendous alarm. A strong consensus has developed that the new guidelines will result in many cancer diagnoses being made later than they would have been under the previous guidelines, causing needless suffering and preventable deaths. Worse, the new guidelines are projected to result in more than 400 Canadian women losing their lives unnecessarily every year. A recent letter signed by more than 130 breast cancer experts states that “the Task Force has ignored copious data published in peer-reviewed journals on the effectiveness of screening mammography in reducing mortality.” The letter further notes that it is dangerous to recommend against screening women aged 40 to 49 since these women represent 24 per cent of the life-years lost to breast cancer, and thus have the most years of life gained when screening is performed. The Canadian Association of Radiologists (CAR) has also called for a review of the new guidelines because they relied on outdated research and lacked input from breast-imaging experts. The CAR supports evidence-based recommendations that average-risk women aged 40 to 49 should have yearly mammographic screening, and average-risk women aged 50 to 74 should have mammographic screening every one to two years. Breast cancer experts are clear: screening tests help detect breast cancer before symptoms develop. Screening can find breast cancer when it’s in its early stages, less likely to have spread and more likely to be treated successfully. And the most reliable way to find breast cancer early in women is mammography—a low-dose x-ray of the breast. In addition, the new guidelines ignore the risks of breast density. According to Dense Breasts Canada, women with dense breast tissue have a much higher chance of being detected late because their dense tissue might mask the cancer. Perversely, while women in the highest category of breast density are at increased risk for breast cancer, the CTF classified them as average risk. And while there is significant evidence supporting the effectiveness of supplementary ultrasounds in detecting cancers missed by mammography in women with dense breasts, the CTF ignored this data. Given these grave concerns, I recently called on the minister of health to put these new guidelines on hold, advise health professionals not to follow them, and launch an evidence-based review under the direction of subject-matter experts. Unfortunately, the minister refused to act on this request. Instead, she responded by saying the guidelines were “independently established by experts,” and that “these are not official government guidelines.” This position is troubling for several reasons. It is incorrect for the minister to call the Task Force members “experts” in this area because the CTF has no breast cancer screening experts in its membership. Of the five doctors on the breast cancer screening working group, two are nephrologists, one is a gastroenterologist and two are family doctors. The chair of the CTF is a psychologist. It is inaccurate for the minister to claim that the federal government has no responsibility for the new guidelines. In fact, the CTF was created by, and receives support from, the Public Health Agency of Canada (PHAC). The Task Force is supported by PHAC’s prevention guidelines division in the Centre for Chronic Disease Prevention Control, which provides scientific and technical support for the development of clinical practice guidelines. Finally, by distancing her government from the new guidelines—instead of fixing them—the minister has left family doctors and other primary health professionals without reliable guidance for breast cancer screening. This abdication will cost women’s lives. No Canadian woman should ever lose her life simply because she wasn’t screened for breast cancer in time. The federal government must therefore act immediately to ensure that Canada’s breast cancer screening guidelines adhere to the doctrine as old as medicine itself: “First, do no harm.” Don Davies is the NDP’s health critic and Member of Parliament for Vancouver Kingsway, B.C. The Hill Times