Women at risk of developing hereditary ovarian and breast cancers can reduce their chances for both diseases by having their ovaries surgically removed, according to researchers at the University of Pennsylvania Cancer Center.
The radical surgery throws a woman into premature menopause by eliminating the organ that produces estrogen, the female sex hormone. But with no early detection tests for ovarian cancer, surgery is often advised for women likely to develop it.
The new study, published in the Journal of the National Cancer Institute, demonstrates that removal of the ovaries also dramatically reduces breast cancer risk for women with mutated BRCA1 genes, which cause inherited forms of ovarian and breast cancer.
The researchers theorize that ovary removal cuts breast cancer risk by reducing exposure to estrogen, which appears to spur the growth of certain tumors.
"The encouraging thing to me is that this tells us hormones are very important in these cancers," said Dr. Timothy R. Rebbeck, the epidemiologist who led the study. "If we can learn more about these hormonal effects, maybe we can develop a pill" that would alter the effects.
The hormonal drug tamoxifen has been shown to help prevent breast cancer in high-risk women, and a second drug, raloxifene, is being tested.
In the study, the researchers looked at more than a decade of medical records of 122 women with BRCA1 mutations. The women, all with strong family histories of ovarian cancer, were tested for BRCA1 mutations after the gene was discovered in 1994.
The researchers estimated these women had an 80 percent lifetime chance of developing breast cancer because of their BRCA1 defects. This risk, however, was reduced by 70 percent among the women who had preventive surgery: 10 of the 43 women who had their ovaries removed developed breast cancer, while 30 of the 79 women with intact ovaries developed breast cancer over the 10-year period.
About a quarter of the women who had their ovaries removed (the average age at removal was 39) subsequently took estrogen replacement therapy, but this did not wipe out the cancer-prevention benefit of surgery, perhaps because the estrogen replacement doses were lower than natural levels, Rebbeck said.
Other researchers, meanwhile, reported today in the journal Cancer that a low-fat diet does not improve the chances of survival for breast cancer patients.
But researchers at Boston's Brigham and Women's Hospital found that a diet rich in proteins from poultry and dairy products significantly lowered the risk of death for these women.
The team based its findings on the landmark Nurses Health Study, which began in 1976. About 121,000 women are involved in the ongoing study, which asks its volunteers to fill out questionnaires on a regular basis.
In another finding from data gathered for the Nurses Health Study, a report in today's issue of the American Journal of Clinical Nutrition says women who eat two to three servings of whole grains daily cut their heart disease risk by 27 percent.