New guidelines, written by the Canadian Task Force on Preventive Health Care, are designed to clarify best practices for screening at a time when many experts and advocacy groups remain sharply divided, particularly about the benefits of routine mammograms for women in their 40s.
The long-time approach to screen early and often has now met a new wave of research and recommendations that concludes that routine mammograms for women in their 40s are of negligible benefit and can lead to needless procedures.
The controversy – playing out against the backdrop of a strapped health-care system that has to make hard decisions about resources and costs – has been stirred by the new national screening recommendations, which say Canadian women under age 50 who are at an average risk of developing breast cancer should not have routine mammograms, and that also advises against self-exams at any age.
In addition to limiting mammograms to women age 50 to 74, the guidelines also say clinical breast exams and self-exams have no benefit and shouldn’t be used; that women aged 50 to 69 should have mammograms every two to three years, instead of every year or two; that women aged 70 to 74 should have mammograms every two to three years – previous guidelines didn’t recommend screening for that age group.
The recommendations don’t apply to women with an elevated risk of breast cancer, such as those with a history of the disease in a first-degree relative or those with mutations in the BRCA1 and BRCA2 genes.
But instead of quelling debate, the recommendations are opening a new chapter in the simmering battle.
While many oncologists and groups such as the Canadian Cancer Society say the new recommendations, published Monday in the Canadian Medical Association Journal, are a balanced approach that will focus breast cancer screening programs on women who can benefit most, others believe the move to limit mammograms to those age 50 and over will put lives in danger.
“We’re really disappointed to see these recommendations,” said Sandra Palmaro, CEO of the Canadian Breast Cancer Foundation, Ontario region. “They’re ultimately going to result in more women dying from breast cancer that don’t need to be dying from breast cancer, there’s no question.”
Provinces are responsible for breast cancer screening programs. Many, such as British Columbia, Alberta and Nova Scotia, regularly give mammograms to women aged 40 to 49, while some others, including Ontario and Newfoundland and Labrador, do not. It remains to be seen whether provinces choose to adopt the new guidelines.
The task force updated the guidelines based on intensive review of international clinical trials, which looked at the risk of developing breast cancer in the various age groups and the potential harms of breast X-rays.
Those harms range from having to repeat a mammogram or getting a biopsy to having a breast removed.
The authors estimated that screening 2,100 women every two to three years for about 11 years would prevent one death from breast cancer.
But it would result in 690 women having false positives that would lead to unnecessary followup testing, including 75 women having an unnecessary breast biopsy.
The College of Family Physicians of Canada endorsed the new guidelines, as has the Canadian Cancer Society, which said the recommendations are aligned with breast cancer screening guidelines from the U.S., U.K., and Australia.
"In particular, there is agreement that regular mammograms for women in their 50s and 60s save lives," the society said in a statement. "Many women are alive and well today because their breast cancer was detected and treated early."
The new recommendations were not universally accepted.
"Since one in six women who die from breast cancer are diagnosed in their 40s, we simply cannot afford to see missed opportunities for earlier detection," said Sandra Palmaro, CEO of the Canadian Breast Cancer Foundation.
The new guidelines frustrated Sarah Simpson of Toronto. At the age of 43, she went to the doctor after feeling pain in one breast.
"If I hadn't had pain, which I was fortunate and incredibly unusual, my cancer would have been in my body eight years before it may have been detected," said Simpson, who is on the board of the Canadian Breast Cancer Foundation. "And eight years later, I hate to think how serious it would be."
Martin Yaffe, a professor in the departments of medical biophysics and medical imaging at the University of Toronto, called the recommendations "scientifically unsupportable."
"If followed, they will result in over 2,000 breast cancer related deaths that could be avoided by screening in Canadian women over 10 years," Yaffe said in an email.
Yaffe said the task force ignored scientific data from studies using modern technology that point to a 25 per cent to 30 per cent reduction in mortality through screening.
Women invariably say they're willing to tolerate the stress of having to come in for more imaging tests in exchange for a better chance of not waiting until a cancer is at advanced stage before it is found, added Yaffe, who is also a senior scientist in imaging research at Toronto's Sunnybrook Research Institute.
The next guidelines will be published within five years, and could include new technology, such as MRI and digital mammography that haven't yet been thoroughly studied.
In a related journal commentary, Dr. Peter Gotzsche of the Nordic Cochrane Centre in Copenhagen, called the new guidelines "more balanced and more in accordance with the evidence than any previous recommendations."
"The main effect of screening is to produce patients with breast cancer from among healthy women who would have remained free of breast disease for the rest of their lives had they not undergone screening," he said.
This year in Canada, an estimated 23,600 women will be diagnosed with breast cancer and an estimated 5,100 will die of the disease.
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