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Breast cancer prevention practices vary across Canada

August 15, 2007

Breast cancer preventive practices for Canadian women carrying the cancer gene vary across the country, says University of Toronto research, and many women are not taking advantage of the options available.

The study, published in the journal Open Medicine, followed the experiences of Canadian women with a BRCA1 or BRCA2 mutation - a genetic mutation that predisposes them to a 87 per cent lifetime risk of developing breast cancer. Women carrying the gene have several options for cancer prevention including prophylactic surgery, chemoprevention and screening; however, researchers observed significant differences across Canada in the uptake of these preventions, with women in Quebec the least likely to use preventive measures.

"We were very surprised by the discrepancy in preventative measures taken across the country," says Professor Kelly Metcalfe, Lawrence Bloomberg Faculty of Nursing, lead author of the study. "The benefit of genetic testing is that we can identify women at high risk of developing breast cancer and hopefully reduce that risk. Ultimately though, women have to elect to undertake one of the options."

In the study, 672 Canadian women were identified as carrying the genetic mutation. Followup questionnaires were completed after a mean of four years. Out of the 342 women without breast cancer after four years, 157 (46 per cent) had not undertaken any cancer prevention option such as a mastectomy, oophorectomy or tamoxifen or raloxifene - drugs used in chemoprevention. Broken down geographically, 39 per cent of women with the genetic mutation in Ontario did not take preventive measures; 34 per cent in Western Canada and 62 per cent in Quebec.

"The numbers show a huge discrepancy, with women in Quebec being the least likely to elect for a preventive option," Metcalfe says. "This will have significant implications in terms of the numbers of cancers we see developing in this high-risk group. We still need to do more research to explain why these differences exist."

University of Toronto