Clinical breast exams are no longer routinely recommended for women at average risk of breast cancer, according to new Canadian guidelines.

That's the main change in Monday's updated guidelines from the Canadian Task Force on Preventive Health Care.

An analysis also found routine mammography, self-examinations and MRIs had no significant benefit for women aged 40 to 49.

The task force also warned there was potential for harm from over-diagnosis and unnecessary biopsy, particularly for younger women.

"We're trying to reframe this set of guidelines away from a prescriptive approach, which makes a one-size-fits-all recommendation for women based on their age, and change it into a discussion between a woman and her doctor about the potential risks, about the potential benefits, and allow each woman to make a decision that's right for her," said Dr. Marcello Tonelli, the chair of the task force and a professor at the University of Alberta's Department of Medicine, in Edmonton.

The guidelines cover women up to age 74 who are at average risk, meaning they have:

- No previous breast cancer.

- No history of breast cancer in a first-degree relative such as a mother or sister.

- No known mutations in the BRCA1 or BRCA2 genes.

- No previous exposure to radiation of the chest wall.

The new guidelines also recommended a change in how often screening mammograms should be offered for women 50 to 74 — from every two years to every two to three years.

As before, there was no evidence that routine breast self-examination in women with no symptoms of breast cancer reduces the risk of death, the panelists concluded in the Canadian Medical Association Journal.

The guidelines cover women up to age 74.

The previous guidelines were from 2001.

Potential for harm

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.

Early detection benefits

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.