The Government of Ontario has announced it is lowering the age threshold for mammogram coverage to age 40, from age 50. The screenings, available every two years, will be covered by provincial health insurance beginning in the fall of 2024, through self-referral via the Ontario Breast Screening Program.

“Nearly 12,000 Ontarians are diagnosed with breast cancer every year,” said Ontario Health Minister Sylvia Jones in her announcement. “We know early detection through regular screening mammograms can save lives, detecting breast cancer before it has the chance to spread.”

Ontario is following British Columbia and Nova Scotia which began the practice in 1988 and 1991, respectively, as well as Prince Edward Island and the Yukon who have set the age of mammogram at 40 for decades. New Brunswick announced new guidelines allowing mammograms at 40, going into effect in early 2024. Alberta has reduced the screening age to 45, and the Northwest Territories, Saskatchewan and Quebec are all indicating they are exploring lowering the age from 50 to 40 or 45 as well.

These decisions are supported by data that indicates earlier detection can be life-saving. According to the Canadian Cancer Society, there is a 100 per cent five-year relative survival rate for breast cancers diagnosed at Stage 1, with the survival rate dropping to less than 25 per cent when the cancer is detected later, at Stage 4. With 17 per cent of breast cancers diagnosed in women aged 40-49, early detection not only prevents death from late-stage cancers, it also can preclude the need for aggressive treatments. The data from Canada on this reflects similar data from a 2023 report by the U.S. Preventive Services Task Force, which also encouraged women to get screened in their 40s.

Breast cancer has been increasing in women under age 50, an age category that’s also at greater risk of mortality from breast cancer. According to the U.S. Task Force report, the number of invasive breast-cancer cases for 40- to 49-year-old women increased an average of two per cent annually between 2015 and 2019. Every case of advanced cancer means heartbreak for families and communities. It also means increased costs for our beleaguered provincial health care systems.

There is a growing dissonance, however, between provincial breast screening guidelines and federal recommendations. The Canadian Task Force on Preventive Health Care (CTFPHC), which was established by the Public Health Agency of Canada (PHAC) to develop clinical practice guidelines, has long maintained that the benefits of mammograms at 40 do not outweigh their harm. Guylène Thériault of the CTFPHC told the Toronto Star earlier this year that the organization is not advising a change in Canada, citing concerns about false positives and overdiagnosis causing women anxiety and leading to interventions that turn out to be unnecessary. According to a 2022 observational study of more than 900,000 patients screened for breast cancer over a 10-year period, seven to nine per cent were flagged for a biopsy.

But the risks of having to undergo a biopsy–typically an out-patient procedure done with local freezing–are small compared to the risk of cancer advancing, according to Jennie Dale, Executive Director of Dense Breasts Canada. Her organization has long advocated to lower the age for a mammogram, co-authoring a 2023 brief on the issue. Dale and her co-advocates point out that the federal task force has ignored research undertaken since 2000, in favour of basing their recommendations on studies from the 1960s, 70s and 80s, lower-quality data that largely excluded women of colour. Moreover, the study that was the greatest influence on the Task Force has recently been shown to be invalid.

Dense Breasts Canada has recently launched an online letter writing campaign calling for the federal task force to commit to using more recent and ethnically diverse data. As of this writing, over 3,700 signatures have been collected.

One problem with having provinces and territories at odds with federal guidelines is that family doctors and nurse practitioners will provide conflicting advice to their patients. Some may follow federal task force guidelines and refuse the necessary referrals, or discourage screening for patients in their 40s, while others will follow provincial guidelines and encourage or allow them.

To make matters worse, an increasing number of patients don’t even have a primary care physician to consult with on this. In Ontario, there are 2.2 million patients without a primary care doctor. Dale points out that some provinces, such as Alberta, where there are more than half a million patients without a doctor, the province sends out appointment invitations in the mail to women when they reach age 45, just as they send out notices for other cancer screenings.

“Without an invitation,” she says, “women will not be aware.”

As we grapple with an epidemic of health misinformation, our federal and provincial/territorial policymakers are confusing the public. While provincial governments and the Public Health Agency of Canada don’t need to march in lock step on every issue, many patients hope they will be able to reach a consensus on breast cancer screening.