Can preventive mastectomies prolong lives?

One of the most painful decisions a woman may ever have to make is whether to undergo a mastectomy to battle cancer. When she has a tumor, she often has little choice. However, as doctors are able to identify healthy women who carry the mutated genes implicated in some breast cancers, a number of women are choosing surgery to head off a high cancer risk.

To aid in this decision, scientists are trying to gauge the value of these voluntary mastectomies.

Since the first of the breast cancer genes was discovered in 1994, debate over such preventive surgery has grown. A new computer model devised at the Dana-Farber Cancer Institute and Harvard Medical School, both in Boston, now suggests that a woman carrying a mutated BRCA1 or BRCA2 gene could add 2.9 to 5.3 years to her life expectancy by having both breasts removed at age 30.

The model aims to help women and doctors assess risks and weigh options, says Jane C. Weeks of Dana-Farber. She cautions that the model is far from the final word on whether doctors should recommend such mastectomies or even test women for the mutations.

"We are trying to create a starting point for these drastic and irrevocable surgeries, to provide a framework for doctors in deciding on strategies that make sense," says study coauthor Deborah Schrag, also of Dana-Farber.

Just having a mutated BRCA gene doesn't ensure that a woman will get cancer, but it increases her odds. Women with either of the mutated genes have a 40 to 85 percent chance of developing breast cancer by age 70, Weeks says, compared to 12 percent for all U.S. women. Women carrying one of the genes also face an elevated risk of developing ovarian cancer--between 5 and 60 percent--compared to 1.5 percent overall.

Removal of the ovaries, or oophorectomy, boosts the life span only 4 to 20 months for a 30-year-old woman carrying one of the mutated genes, the model shows. Having both operations would add slightly more years than a mastectomy alone, the researchers report in the May 15 New England Journal of Medicine (NEJM).

For a woman who has a mutated gene as well as a family history of breast or ovarian cancer--and thus could face an 85 percent likelihood of getting cancer--preventive mastectomy and oophorectomy at age 30 would add 7.6 years.

The value of preventive mastectomies diminishes with age, the model reveals. A 40-year-old carrier of a faulty BRCA gene would add 2 to 3.7 years to her life expectancy, whereas a 60-year-old would gain less than 1 year.

Because the BRCA genes were discovered only recently, researchers lack long-term studies that would provide a measure of the worth of preventive mastectomies, Weeks says.

Even so, these operations appear to be brutally effective. Lynn Hartmann of the Mayo Clinic in Rochester, Minn., reports that in an ongoing study of nearly 300 women who had a strong family history of breast cancer and who had a preventive double mastectomy between 1960 and 1993, only two developed cancer in the breast area later.

Hoda Anton-Culver of the University of California, Irvine says that, in the absence of a long-term study of women with a BRCA gene, "a modeling study is a good thing to have."

Bernadine Healy, former director of the National Institutes of Health and now at Ohio State University in Columbus, warns in an editorial in the same issue of NEJM that research into breast cancer genetics "is in danger of being overwhelmed by a flood of information on odds making and fortune-telling that is affecting the care of individual patients."