About 5 to 10% percent of women with breast cancer have an inherited mutation in the BRCA1 or BRCA2 gene, which puts them at greater risk for developing breast and ovarian cancers. For most women diagnosed with early-stage breast cancer, having a BRCA mutation doesn’t affect how the cancer itself is treated. But the presence of a BRCA mutation can present patients with an array of choices about lowering their risk of a future cancer.
For women diagnosed with stage I-III breast cancer, which has not metastasized to other parts of the body, treatment is based on factors such as the tumor’s size, whether cancer cells are found in lymph nodes in the underarm, and whether it is classified as hormone receptor-positive, HER2-positive, or triple- negative, says Philip Poorvu, MD, a breast cancer specialist at Dana-Farber. A patient’s BRCA status — whether the cancer does or doesn’t carry a BRCA mutation — normally doesn’t factor into the treatment of the cancer itself.
That hardly means that BRCA status is irrelevant, however. People who test positive for an inherited BRCA mutation may decide to take steps to reduce the chance that they’ll develop another breast cancer, often by undergoing a bilateral (or double) mastectomy. Some women may choose to have additional screening rather than a mastectomy. Although screening does not prevent the development of cancer, it aims to detect it earlier. Women with BRCA mutations are also at increased risk of ovarian cancer and are recommended to undergo the removal of the ovaries and fallopian tubes once they are done having children or by age 35-40.
Inherited BRCA mutations may also have consequences for patients interested in having children after breast cancer treatment, Poorvu continues. There is a 50% chance of passing the mutation on to each child, male or female. Some women in this position opt to undergo in vitro fertilization followed by a procedure in which newly formed embryos are tested for BRCA mutations. Those without mutations would be selected for implantation in the woman to initiate a pregnancy to avoid passing on the BRCA mutation.
People who carry inherited BRCA mutations also face the issue of how to inform relatives about the results of their BRCA testing. These relatives may also have a BRCA mutation, potentially increasing their own or their children’s risk of breast, ovarian, or other cancers. Genetic counselors help patients understand the implications of genetic testing and genetic results and how to approach discussion with family members.
Patients for whom BRCA status can affect treatment are those with metastatic, or stage 4, breast cancer. These patients may be eligible for treatment with drugs known as PARP inhibitors, two of which — talazoparib and olaparib — have been approved by the FDA for patients with specific types of breast cancer.
Studies are currently under way evaluating other drugs that may also work particularly well on breast cancers in women with BRCA mutations, Poorvu states.