Breast screening at age 40 not routinely advised, Canadian task force says

People should be able to get a mammogram starting at age 40 but it shouldn't be routinely offered to women under 50 who are of average risk, new Canadian screening guidelines suggest.

The Canadian Task Force on Preventive Health Care is an organization created by the federal government to develop clinical practice guidelines in areas like cancer to guide family physicians and their patients. The members include family doctors, nurse practitioners as well as cancer specialists and patient partners.

The task force "does not recommend regular screenings for women under 50 who are of average risk," a spokesperson said in an email to CBC News on Thursday. "However, the task force believes breast cancer screening is a personal choice, and that any woman who wants a screening should be able to get one."

The task force said if someone of average risk age 40 and over understands the benefits and harms of early screening and wants to have it, they should be able to get a mammogram every two to three years. It noted the risk of harms such as unnecessary tests and anxiety.

Screening aims to catch a disease like breast cancer before it causes any problems that are noticeable by the patient. In contrast, diagnostic tests are done when someone shows symptoms, such as a lump.  

Earlier this month, the Canadian Cancer Society called for breast screening to routinely begin at age 40, a target many provinces and territories are moving toward.

When researchers at the University of Ottawa compared breast cancer statistics from provinces that screened women in their 40s to data from provinces that followed the task force guidelines, they concluded earlier screening led to significantly improved survival rates.

Women aged 40 to 49 can self-refer to a breast screening program in Yukon, British Columbia, Nova Scotia, Newfoundland and Prince Edward Island, according to the Canadian Cancer Society. Ontario will start covering screening mammograms for women in their 40s this fall.

The Northwest Territories and Alberta have recently lowered program start age from 50 to 45, and Saskatchewan recently announced that it will lower its program start age to 40, using a phased-in approach beginning in 2025, the society said.

New Brunswick is also moving toward earlier screening with self-referral.

Breast cancer is a major health concern in Canada, with one in eight Canadian women diagnosed in their lifetime.

Dense Breasts Canada, a group that advocates for better screening and awareness of optimal breast screening, is disappointed in the task force recommendations.

The breast is made up of fat and normal breast tissue composed of glands, fibrous tissues and more. Breast cancer looks white on a mammogram, as does normal breast tissue. When a woman has a larger proportion of normal dense tissue, it can be more difficult to spot cancer on a mammogram, Dr. Paula Gordon, a breast radiologist and a clinical professor in the University of British Columbia's radiology department, has said. 

Other risk factors for breast cancer include age, a family history and genetic mutations, oncologists say.