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A Radiologist talks with a patient over a mammogram at a radiation clinic in Toronto on Wednesday, April 20, 2005.

Provinces are reviewing their breast-cancer screening programs in light of new national guidelines calling for a sharp reduction in mammograms.

The guidelines from the Canadian Task Force on Preventive Health Care, released Monday, have sparked a fiery national debate over which women should receive X-rays and how often. The provinces and others are now taking a fresh look at their rules and examining whether they should be changed

While most provinces and territories have encouraged women in their 40s to get regular mammograms, Canada's most populous province hasn't since its screening program began about two decades ago. Ontario doesn't expect to change this policy, noting its rule aligns with the task force's position.

"Our interpretation and synthesis of the evidence in the past and up to the present time has been … the evidence was not sufficiently strong to recommend routine screening for that group of women," said Linda Rabeneck, vice-president of prevention and cancer control with Cancer Care Ontario. (The province recommends women with a high risk of breast cancer due to family history or a genetic mutation receive screening.)

Other provinces such as British Columbia, Alberta and Prince Edward Island have offered mammograms to women in their 40s under the belief early detection is essential to preventing advanced stages of cancer and deaths. These provinces and others are now taking a fresh look at their rules and examining whether they should be changed.

The Canadian Task Force on Preventive Health Care, a scientific panel established by the federal Public Health Agency, was tasked with sorting out conflicting signals on the benefits of mammograms that have arisen through several international studies of screening programs.

The panel, which includes 15 primary care and prevention experts, is advising against routine mammograms for most women in their 40s, contending the potential harm caused by false positives and unnecessary biopsies outweighs the small reduction in deaths. It also suggests clinical breast examinations and self-exams offer no benefit and women 50 to 69 should have breast X-rays every two to three years, instead of every year or two.

British Columbia, the first province in Canada to introduce a program to screen for breast cancer, began a review of its policies even before the task force unveiled its recommendations. The province's cancer agency will consider the new guidelines. B.C. offers regular mammograms to women between the ages of 40 and 79. A referral from a doctor isn't required.

Last year, 303,157 examinations were performed on 302,957 women through British Columbia's screening program. About one-third involved women under 50, and overall screening costs were about $33-million.

In Ontario, the cost of screening did not factor into the province's decision to advise women in their 40s against regular mammograms, Dr. Rabeneck said. Still, controlling health-care expenditures is a pressing challenge facing all provinces as they grapple with escalating costs and an aging population that requires more medical care.

Martin Yaffe, a senior scientist in the imaging research program at Sunnybrook Research Institute in Toronto, doesn't believe the availability of mammograms should be reduced, but concedes the cost-effectiveness of screening needs to be evaluated.

He is leading a study on this matter. Funded by the Canadian Breast Cancer Foundation, the probe includes a health-care economist from the Toronto-based Institute for Clinical Evaluative Sciences and two American consultants who have examined mammography costs outside of Canada. B.C. estimates it costs around $16,000 per cancer detected through screening.

"There's a general need to have numbers on the table to understand whether it's cost-effective to do screening or not," Dr. Yaffe said. His study is expected to be completed by the fall of 2012.

Epidemiologist Cornelia Baines of the University of Toronto has examined the medical effectiveness of screening for more than two decades. She believes the task force's recommendations are sensible and the use of mammograms should be curtailed, noting breast-cancer mortality is dropping in populations that aren't being screened.

"The therapies in the last 30 years have become much more effective," Dr. Baines said. "And women became aware of the fact they had a breast abnormality and they weren't ashamed to take it to the doctor."

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