Breast screening has become a divisive topic in recent months, since a draft decision by a national U.S. task force to call for mammograms starting at age 40, a decision that was finalized with the publication of new guidelines last month.Damian Dovarganes/The Canadian Press
Canada’s largest cancer charity has entered the highly charged debate on routine breast screening, urging provinces and territories to offer mammograms at age 40 to save lives and address a growing call for earlier interventions.
The Canadian Cancer Society published its updated position statement on Thursday, ahead of the planned release this spring of new national guidelines on routine breast screening for average-risk individuals.
“We believe really strongly that people in Canada should have fair and timely access to breast screening, regardless of where they live and who they are,” said Sandra Krueckl, executive vice-president of mission, information and support services at the Canadian Cancer Society.
Breast screening has become a divisive topic in recent months, since a draft decision by a national U.S. task force to call for mammograms starting at age 40. That decision was finalized with the publication of new guidelines last month.
The influential charity’s call to action puts increased pressure and scrutiny on the Canadian Task Force on Preventive Health Care, which is responsible for developing clinical practice guidelines, including cancer screening recommendations. While the guidelines are not binding, many jurisdictions use them to set their own policies.
Some provinces already allow individuals access to screening mammograms at age 40. Last fall, Ontario announced it would lower the screening age to 40, after calls from advocacy groups to make the change.
The federal government gave the task force an additional $500,000 last year to expedite the creation of the new guidelines, which were expected to be released last fall. They have been delayed until some time this spring as members continue to mull over the available data.
In a statement, the Canadian Cancer Society cites “evolving evidence” and a groundswell of public support for earlier screening in its decision.
Many breast cancer advocacy groups and disease survivors in Canada say the U.S. policy change should be the impetus for a similar move here. This country’s national screening recommendations, last updated in 2018, call for routine mammograms to start at age 50 and for individuals to make informed decisions about what’s best with their health care provider.
Spokesperson Kim Barnhardt said in an e-mail statement that the Canadian Task Force on Preventive Health Care “respects” the cancer society and its important work.
“We look forward to discussing the draft recommendations on screening for breast cancer from our comprehensive evidence review later this spring,” the statement said.
The issue is complex. While the clinical evidence for screening mammograms in people 50 and older shows a clear benefit, the data are murkier in younger people. For women in their 40s, breast cancer rates have been slowly increasing in recent years, although the overall incidence remains fairly low. While mammograms can catch cancer early, before it progresses, screening women in their 40s also exposes individuals to the risk of false positives and unnecessary biopsies.
Dr. Krueckl said about 13 per cent of all breast cancer cases happen to women aged 40 to 49. There has been a small increase in that cohort, about a quarter of a per cent, each year in the past few years, she said.
According to the U.S. Preventive Services Task Force, if 1,000 women in their 40s have mammograms every two years for a decade, two of them will die from breast cancer in the next 10 years. Among those who forgo mammography, three will die, which means screening resulted in one less death. At the same time, of those who undergo regular screening, the task force says 36 per cent will experience a false alarm; nearly 6 per cent will have an unnecessary biopsy; and two women will be overdiagnosed with a cancer that never would have posed a health risk.
Christopher Labos, a cardiologist and an associate with the Office for Science and Society at McGill University, which promotes critical thinking and science communication, said there is no clear answer on which age is the best age to start screening for breast cancer.
“It’s really just a question of the magnitude of the benefit you’re trying to get,” he said.
Dr. Labos said he believes that new, robust trials of different breast screening methods, including mammograms, ultrasound and MRIs, should be done to better understand which works best in younger and older women.
While mammograms work, there may be tradeoffs for some individuals, such as unnecessary biopsies. And people who get screened could still develop a fast-growing tumour six months later that will go undetected.
“There is a lot of nuance to this argument,” he said.
Breast cancer screening refers to programs that look for cancer in people who are not experiencing any symptoms. If an individual has symptoms, such as a lump, the mammogram is used to diagnose, not screen. And the current screening guidelines don’t apply to people who have a family history or genetic mutations that put them at a higher risk for breast cancer.
Dr. Krueckl said a number of factors make the issue complex, but the society believes screening at 40 is the way to go for average-risk individuals.
“There is no absolute answer, but the Canadian Cancer Society really strongly believes that is important to give people access to screening that can save their lives,” she said.