May 2001

From University of Toronto

Tubal ligation reduces risk of ovarian cancer by 72 per cent in high-rish women

Toronto, Ont. (May 9, 2001) -- A new study in The Lancet suggests that tubal ligation can reduce the risk of hereditary ovarian cancer by 72 per cent in women who carry the BRCA1 gene.

Women who inherit a mutation in the BRCA1 or BRCA2 genes are far more likely than the general population to develop breast and ovarian cancer. The results of a matched case-control study of 232 women with a history of invasive ovarian cancer in Canada, the United States and the United Kingdom has prompted the authors to recommend that tubal ligation be offered to women with BRCA1 mutations as a means of reducing ovarian cancer risk.

Dr. Steven Narod, a molecular epidemiologist at the Centre for Research in Women's Health, led the study in which the risk for developing ovarian cancer was estimated for tubal ligation. In Canada, one in ten women with ovarian cancer are estimated to carry the BRCA1 gene mutation. Preventive measures to date have commonly included prophylactic oophorectomy (removal of the ovaries), oral contraceptives and regular ultrasound and serum screening.

"Many women at high risk for ovarian cancer choose to have their ovaries removed, but few women choose this before 35 years of age. Offering tubal ligation as soon as childbearing is complete is reasonable and can be followed by removal of the ovaries at a later date," says Dr. Narod, associate professor of public health sciences in the University of Toronto's Faculty of Medicine. The side effects of tubal ligation are minimal, while oophorectomy can cause menopausal symptoms like hot flashes and vaginal dryness.

The study observed a strong protective effect of oral contraceptives against ovarian cancer risk. The combination of oral contraceptives and tubal ligation offered greater protection than either method alone. The study did not indicate that tubal ligation has a protective effect among BRCA2 carriers, only BRCA1 carriers.

"Obviously, women stop taking oral contraception after a tubal ligation. It would be interesting to examine the preventive merits of combining oral contraception and tubal ligation," adds Narod.

This research study was supported by the National Cancer Institute of Canada, the Canadian Genetic Diseases Network, the Canadian Breast Cancer Foundation (Ontario Chapter), the Fonds de la Recherche en Sante du Quebec and the Chair in Breast Cancer Research, which Dr. Narod has held since 1996.

The Centre for Research in Women's Health was founded in 1995, and is a partnership of the University of Toronto and Sunnybrook and Women's College Health Sciences Centre. The Centre is committed to conducting and fostering women's health research which is relevant to women's lives, and to promoting its application in diverse communities.












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