In 2009 the U.S. Preventive Services Task Force recommended against routine mammograms for women in their 40s. That caused a political firestorm then, with ill-informed politicians claiming that bureaucrats were trying to hold back a lifesaving test to save money. The truth was, and is, that mammograms cause more harm than good unless the women being tested are already at significant risk.
Now, Canadian health-care watchdogs have echoed the U.S. opinion, and for the same reasons.
As reported in CMAJ, the Canadian Medical Association journal, the Canadian Task Force on Preventive Health Care says routine mammograms for women 40-49 are not necessary if they are at average risk of contracting the disease. Women with a personal/family history of breast cancer, or who have the BRCA1/BRCA2 gene mutations are at higher risk, and should be screened more often.
The report concludes that although mammography screening can reduce death from breast cancer among women aged 40–74 years, “the absolute benefit is small – especially for younger women – and is partially offset by harms caused by unnecessary intervention.”
Those harms include false positives, which prompt additional screening or tests that usually include more radiation exposure, uncomfortable biopsies and high anxiety. The disease is relatively rare in younger women, and their higher breast density compromises the ability of mammograms to be fully useful. So the Canadian report says that for women at average risk, an interval of two or three years is sufficient for mammography screening.
Like the earlier U.S. task force, the Canadians emphasize that providers and patients consider the benefits-harm trade-off when deciding about having a mammogram.
In addition to questioning the wisdom of screening younger women via mammography and magnetic resonance imaging, this task force also said that there is no evidence that “clinical breast examination or breast self-examination reduces the risk of mortality or other clinically relevant adverse outcomes.”
Here’s what the Canadian task force recommends for mammography screening for women at average risk, by age:
- 40–49 years, no routine screening;
- 50–74 years, routine screening every two to three years.