Removal of the Ovaries May Prevent Breast Cancer in Women Most At Risk

Those genetically prone to cancer can benefit, studies find

Women who have their ovaries removed to protect against an inherited form of ovarian cancer also reduce their risk of breast tumors, two new studies have found.The procedure, called prophylactic oophorectomy, almost completely eliminates the risk of ovarian cancer. In the process, by shutting off the supply of estrogen, the operation reduces the risk by almost threefold of breast cancers triggered by the sex hormone.

BRCA Gene Mutations

Both cancers are much more common in women with two errant forms of a gene called BRCA. Experts say the latest findings apply only to women with the BRCA1 and BRCA2 mutations, who make up only about 0.1 to 0.2 percent of women in the United States. The genes are particularly common in Jewish women of Eastern European descent.

Yet despite their low numbers, these women account for 10 percent of all ovarian cancers, up to 10 percent of all breast cancers in women under age 40, and as many as three-quarters of inherited breast cancers in families with three or more affected women.

The two studies appear in a recent issue of the New England Journal of Medicine. The researchers also presented their findings recently at a meeting of the American Society of Clinical Oncology in Orlando, FL.

Timothy Rebbeck, a University of Pennsylvania cancer expert and lead author of one of the papers, says the results confirm clinical recommendations physicians have been making to women with either of the two tumor mutations.

"One of the problems up until today was that there really wasn't a lot of data" to support those recommendations, Rebbeck says. "This might change some peoples' minds for those on the fence."

Making Better Decisions About Your Healthcare

Dr. Kenneth Offit, chief of clinical genetics at the Memorial Sloan-Kettering Cancer Center and a co-author of the other paper, says the findings should help women with the BRCA mutations make better decisions about their care.

"This is information that's going to help women to decide between a prevention option and a screening option," Offit says. "These results show that the prevention option can, in our study, decrease the risk for both ovarian and breast cancer by up to 75 percent in women at the highest risk" for the diseases.

Sue Friedman, founder of FORCE, a non-profit group for women with BRCA mutations, lauded the two studies.
"While we are pleased that the results of these studies confirm” the value of preventive ovary removal, she says, "we look forward to the time when advances are made that obviate the need for surgery in order to lower cancer in high-risk populations."

Study Results - The First Study

In the first study, Rebbeck and his colleagues analyzed the medical histories of 551 women with the BRCA1 or BRCA2 mutations. Of those, 259 had had both ovaries removed.

In a sub-group of 241 women with no history of breast cancer, and over at least eight years of follow-up, breast tumors occurred in 21 of 99 women (21 percent) who had ovary surgery. That compares with 60 of 142 (42 percent) women with who did not undergo the operation.

Nearly 20 percent of the untreated women went on to develop ovarian cancers, while only two women, or less than 1 percent, were diagnosed with peritoneal cancer in the years after the surgery. Those tumors are believed to be seeded by residual ovary tissue left behind after surgery. Like ovarian cancer, they are difficult to catch early and are quite lethal when diagnosed in advanced stages.

Study Results - The Second Study

Scientists at Memorial Sloan-Kettering Cancer Center led the second study. Rather than look back at a group of women 35 or older who had already had their ovaries removed, the researchers followed patients from the time they elected to have the surgery.

After an average of two years later, three of the 98 women who had had their ovaries taken out—less than 3 percent—had developed breast cancer, compared with eight of 72 women—or 11 percent—in a comparison group that opted for close monitoring over surgery.

Four women in the untreated group went on to develop ovarian tumors, and one had peritoneal cancer, compared with just one case of peritoneal cancer in the surgery arm.

Removing the ovaries —and, in the New York study—the fallopian tubes, too, triggers menopause. So, women may feel conflicted about having the procedure while they can still bear children. However, Rebbeck says it appears it is safe to wait to have the surgery.

Although the trends look promising, "the story is by no means closed," Offit says. "We need to have longer follow-up to actually show ultimately that there is improvement in mortality."

Always consult your physician for more information.