Chemoprevention, or taking medication to reduce breast-cancer risk, is another option. However, the medications -- such as Tamoxifen, an estrogen blocker -- are only suitable for some women, and can increase the risk of blood clots and uterine cancer, the Komen Foundation says. There is also little information regarding how much the treatment reduces breast-cancer risk among BRCA-mutation carriers, and researchers are still studying which high-risk women would benefit most from the treatment.
BRCA mutations are not common; in the general population, about 1 in 400 people have BRCA mutations, according to the National Cancer Institute. And BRCA mutations account for just 5 to 10 percent of breast cancers and 15 percent of ovarian cancers, according to the Mayo Clinic.
Women with BRCA mutations are at increased risk for breast and ovarian cancer, though the exact risk for an individual will vary depending on other factors.
The average woman in the United States has an 12 percent chance of getting breast cancer by age 85, according to the Komen Foundation. Some studies show that women with mutations in the BRCA1 gene have a 50 to 70 percent chance of getting breast cancer by age 70, and women with mutations in the BRCA2 gene have a 40 to 60 percent chance, the foundation says.
Factors such as having a family member with breast cancer, as Jolie did, further increase breast-cancer risk, said Annette Lee, an associate investigator at the Feinstein Institute for Medical Research in Manhasset, New York.
The BRCA1 and BRCA 2 genes are thought to keep cancer in check by repairing damage to DNA, Lee said. Mutations in these genes interfere with this repair.
"If you can't repair DNA, you accumulate mutations, and that contributes to the development of cancer," she said.
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