Women who have the gene mutations BRCA1 or BRCA2 can reduce their likelihood of developing ovarian cancer and breast cancer by having prophylactic surgery to remove both ovaries, according to two new studies in the New England Journal of Medicine.
However, because removing both ovaries substantially lowers the production of hormones, the researchers said there is some concern that hormone replacement therapy—which is required after the surgery—could raise the risk of cancer by restoring some of these hormones.
Previous studies showed that women who carry the BRCA1 or BRCA2 mutation have a 60-85% risk of developing breast cancer by age 70 and a 15-65% risk of developing invasive ovarian cancer.
In the study by Dr Timothy Rebbeck, of the University of Pennsylvania, and colleagues, the researchers found that women with either of the mutations who had both ovaries removed reduced their risk of ovarian cancer by 96% and their risk of breast cancer by 53% .
The patients were followed for eight years, during which eight of the 259 women who had their ovaries removed developed ovarian cancer or papillary serous peritoneal carcinoma, a related cancer. Six of these cancer cases were detected during the surgery to remove the patients' ovaries, so the actual percentage of women who developed ovarian related cancer after surgery was less than 1% About 20% of women who had not had an ovary removed developed ovarian cancer.
In the other study, a team led by Dr Kenneth Offit at Memorial Sloan-Kettering Cancer Center in New York found that bilateral salpingo-oophorectomy also greatly reduced the risk of both ovarian and breast cancer (2002;346:1609-15).
This study looked at 170 women aged 35 and older who had a BRCA1 or BRCA2 mutation. The women were given a choice to have their ovaries and fallopian tubes removed or to be closely monitored for signs of ovarian cancer. During an average of about two years follow up, three of the 98 women who had surgery developed breast cancer and one woman developed peritoneal cancer. Among the 72 women who did not choose surgery, there were eight new cases of breast cancer, four of ovarian cancer, and one of peritoneal cancer.
The two studies “contribute to mounting evidence” that women who carry BRCA mutations can reduce their risk of both ovarian and breast cancer by having both ovaries removed, said Dr Daniel Haber of Massachusetts General Hospital in Charlestown in a related editorial.
“Whether the resulting reduction in the risk of breast cancer, combined with intensive surveillance, is preferable to the more complete protection offered by prophylactic mastectomy is likely to remain a highly personal choice,” he wrote.
Figure.
Estimates from the study led by Dr Kenneth Offit