By Nathan Seppa, Science News
Surgical removal of the ovaries lessens the risk of death in women carrying a BRCA mutation linked to breast and ovarian cancer, a new study shows. The research also indicates that women undergoing this operation or a mastectomy limit their risk of ovarian or breast cancer, bolstering previous findings that these operations offer long-term protection (SN: 5/25/2002, p. 323). The new study appears in the Sept. 1 Journal of the American Medical Association.
“This is really the first study to show that these women live longer” if they get their ovaries taken out, says Virginia Kaklamani, a medical oncologist at Northwestern University School of Medicine in Chicago.
The BRCA gene encodes a protein that protects against cancer. But women carrying a mutated form of the gene face a 50 to 80 percent lifetime risk of developing breast cancer and also have a heightened risk of ovarian cancer.
In the new study, scientists collected genetic data on 2,482 women who were seen by a doctor between 1974 and 2008. All of the women eventually were found to be positive for a BRCA mutation. Data collected on some of the women in this study predated the discovery of the BRCA mutations in the mid-1990s. Thus, the genetic status of those women was determined retrospectively.
Overall, about two in five had chosen to have their ovaries surgically removed, and roughly one in five had elected mastectomy, says study coauthor Timothy Rebbeck, an epidemiologist at the University of Pennsylvania School of Medicine in Philadelphia. Some women had both operations. The women were monitored for nearly four years on average.
During follow-up, 3 percent of the women who had undergone ovary removal subsequently died, compared with nearly 10 percent of women who didn’t have the operation. Having the operation also decreased the risk of dying from breast cancer, particularly in women who had previously had breast cancer. Only 1 percent of women getting the ovary surgery developed ovarian cancer, compared with 6 percent of those who chose to forego ovary removal.
The researchers did not calculate mortality in mastectomy patients, but they did find that among women with no previous history of breast cancer, having their breasts removed as a preventive measure worked: None of these 172 women had breast cancer subsequently. In contrast, 7 percent of those who decided to forego mastectomy developed breast cancer.
Women who have had breast cancer or who have a family history of breast or ovarian cancer, particulary if they are Ashkanazi Jewish, should consider getting the genetic test to discern whether they have a BRCA mutation, Kaklamani says. If they are found to harbor the mutation, the next step would be to consider ovary removal, a step that is recommended by medical oncology organizations for mutation-positive women after they have passed their childbearing years, she says. The operation can be done laparoscopically and is much less invasive than mastectomy.
No one knows the actual incidence of the BRCA mutation in the population, says gynecologist and cancer geneticist Noah Kauff of Memorial Sloan-Kettering Cancer Center in New York. He estimates that fewer than 10 percent of women and men who have the mutation have been identified in the United States.
On a more positive note, Kauff also believes that among women who know they are positive for the BRCA mutation, a greater fraction has had elective ovary removal than the new dataset reflects. A 2008 study in which Kauff teamed with Rebbeck and others to analyze the status of women from 1994 to 2004 found that 64 percent had had the surgery.
Mastectomy is a more delicate topic, and acceptance varies greatly between ethnic groups, Rebbeck says. For example, preventive mastectomy is fairly common in Northern Europe. “In Southern Europe, it’s almost unknown,” he says.
The new study offers information accumulated by prospectively tracking women as they lived with a decision to have an operation or not. “Women themselves can now look at the data tables,” Rebbeck says. “This helps women and their clinicians make decisions.”