By William J. Cromie

Gazette Staff

Women whose genes make them susceptible to cancer may be able to add three to five years to their lives by having their breasts removed before they get the disease. The same group of women might live an additional 4 to 20 months by having their ovaries removed, according to Medical School researchers.

These are women who have mutations in either of two genes known as BRCA1 and BRCA2. Forty to 85 percent of women who inherit mutated forms of these genes develop breast cancer, and 5-40 percent get ovarian cancer.

Such women represent an estimated 5 to 10 percent of all breast cancer and 5 percent of ovarian cancer cases in this country. "No one knows exactly how many women are involved," says Deborah Schrag, an instructor in medicine and one of the researchers. "BRCA1 and 2 weren't found until 1994 and 1995, respectively. But we're only talking about a small minority of women here."

Schrag also points out that such surgery is never 100 percent effective. She and her colleagues estimate that about 85 percent of breast cancer and 50 percent of ovary cancer cases will be successfully prevented.

Their conclusions come from a computer analysis of the latest information on life expectancies among women with the mutated genes done at the Dana-Farber Cancer Institute.

"In reporting our findings, we are not advocating either of these procedures, but are seeking to assist women and their doctors by clarifying the potential impact these diseases might have on overall survival," Schrag notes. "Also, our analysis does not include the impact of such surgery on the quality of life."

The younger a woman, the more she would gain from this kind of surgery, the researchers say. For example, a 30-year-old woman with these genetic mutations and a family history of these cancers might increase her life span as much as five years, four months as a result of breast surgery and almost two years with ovarian surgery. Those in their 60s, on the other hand, would gain little.

For women with the mutations who have not had children, the analysis predicts that delaying ovary removal until age 40 would produce only a small decrease in life expectancy gain.

In their report, published in today's New England Journal of Medicine, Schrag and her colleagues compare the gains from preventive surgery to those from other health measures. A 35-year-old woman with moderately high blood pressure, for example, could add almost two years to her life expectancy by controlling her condition with diet, exercise, and drugs. The same-age woman might gain an extra six years of life by getting an extremely high cholesterol level down into a normal range.

Study co-author Jane Weeks, assistant professor of medicine, notes that the findings must be carefully interpreted.

"A life expectancy gain of four years does not imply that an individual can anticipate a guarantee of an extra four years," she says. "Rather, life expectancy gains reflect the average effect on survival of a group of people of defined age and level of risk. By providing estimates that create a starting point for the consideration of these difficult issues, our analysis offers a framework that may help at-risk women and their doctors choose the prevention strategy that is best for them."