After the U.S. Preventive Services Task Force updated its mammogram guidelines for screening to begin at 40, its Canadian counterpart was pressured to lower its recommended age, as well. They’ve decided not to do so.

The Canadian Task Force on Preventive Health Care has just issued new draft breast screening guidelines. In them, the group said women in their 40s should be provided information about the benefits and harms of screening. If after receiving this information, they still want to go ahead with a mammogram, they should be able to get one every two to three years. However, regular screening is still not recommended until age 50.

Dr. Guylène Thériault, a family physician and chair of the task force and breast cancer working group, says, “We all want to find ways to reduce the burden of this disease and improve outcomes. People may find that information about breast cancer screening is surprising – there are potential benefits to screening, but there are also harms. We want women to have all the information they need to make the decision that’s right for them.”

Information should include how age, family history, race and ethnicity, and breast density can impact benefits and harms. Possible harms, the group says, include additional imaging, unnecessary biopsies, and overdiagnosis.

The task force – which consists of oncologists, patient partners, family physicians, and other experts – reviewed more than 160 studies to develop their draft recommendations. They say that evidence suggests harms outweigh the benefits for screening patients in their 40s, while most patients may not feel the benefits outweigh the harms.

They did note that data shows there are racial differences in incidence, mortality, subtype, and stage at diagnosis, particularly for Black women, but there isn’t enough data on benefits and harms or on values and preferences by race. For women with dense breasts, who are also at an increased risk of breast cancer and for whom mammograms aren’t as effective, the task force does not recommend additional screening with MRI or ultrasound. However, they do say more research is needed on both topics.

Dr. Eddy Lang, an emergency physician at the University of Calgary and task force member, explains, “We join the United States Preventive Services Task Force in calling for more research on the impact of screening in Black and other racialized populations, and more research on supplemental screening for those with dense breasts.”

As it stands, screening is broadly recommended every two to three years for women between the ages of 50 and 74. At the age of 75, it’s recommended that screening cease.

The recommendations come as the task force has been pushed to lower its screening age. Proponents of this change include the Canadian Cancer Society (CCS), which says the starting age should be 40 to “reflect evolving evidence.”

Dr. Sandra Krueckl, Executive Vice President of Mission, Information and Support Services at CCS, says, “The issue of breast screening is complex and there has been a debate among experts on the best age to begin screening. Over the last several years, there has been a groundswell of support for screening to begin at a younger age and for a more inclusive system – one that empowers people between the ages of 40 and 49, no matter where they live, to access screening without barriers. We need to heed that call, as well as ensure there is clear guidance for people who have an elevated or high risk of developing breast cancer, such as people with genetic mutations, family history or dense breasts.”

Concerned Canadians can share their thoughts throughout a public comment period. The link to do so is here.