Gauging an at-home test for breast cancer
DEAR DOCTOR: I don’t have a history of breast cancer in my family, but now that there’s an at-home test for the BRCA mutations, should I get tested just in case?
DEAR READER: The at-home test assesses the BRCA1 and BRCA2 genes. For starters, they’re tumor-suppressor genes, producing proteins that aid in the repair of damaged DNA molecules. If the proteins produced by the BRCA genes don’t work appropriately, abnormal cells with DNA mutations will not be repaired but will instead divide to create more abnormal cells. This is one of the ways cancer can develop.
Among women with a mutation in the BRCA1 gene, 72 percent will develop breast cancer in their lifetime and 44 percent will develop ovarian cancer, research has found. Among those with a BRCA2 mutation, 69 percent will develop breast cancer and 17 percent will develop ovarian cancer. Among women with a family history of breast cancer, 20 percent of those cancers are related to the BRCA gene. Certain ethnic and geographic groups are more likely to have BRCA mutations, with Ashkenazi Jews especially likely to have such mutations.
The at-home test was recently approved
by the FDA to measure mutations. The big caveat is that the test detects only three of the BRCA mutations, meaning that it won’t pick up the multitude of other possible mutations in the BRCA genes. These other mutations have to be identified by more involved tests that assess the complete BRCA genes. Nor does it identify mutations beyond the BRCA genes that can increase the risk of breast cancer.
That’s not to say it can’t be useful for some people. Ashkenazi Jewish women would be good candidates for such screening.
Women with a close family history of breast cancer, however, would be better advised to undergo complete DNA sequencing of the BRCA genes. This specialized test, ordered by a physician, is more likely to detect other breast cancer-related mutations. In the future, with our greater abilities to quickly test for genetic abnormalities, at-home tests will be more comprehensive.
Robert Ashley, M.D., is an internist and assistant professor of medicine at the University of California, Los Angeles.
Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA 90095.