Anticancer agents that act by damaging DNA, such as cisplatin, can be effective treatments for tumors that develop in people who have inherited harmful changes in BRCA1 or BRCA2 because the mutated genes cause defective DNA repair (46). Cancer cells that cannot repair DNA damaged by cisplatin or similar chemotherapy drugs are more likely to be killed by these drugs.
Cancer cells that have harmful changes in BRCA1 or BRCA2—whether the changes are inherited or occur during life—can also be treated effectively with drugs called PARP inhibitors, which block the repair of DNA damage. Four PARP inhibitors—olaparib (Lynparza), rucaparib (Rubraca), niraparib (Zejula), and talazoparib (Talzenna)—are approved by the FDA to treat certain cancers bearing harmful changes in BRCA1 or BRCA2.
Breast cancers in people with inherited harmful changes in BRCA1 are more likely than breast cancers that develop in people without these gene changes or people in the general population to be triple negative (that is, to lack estrogen receptors and progesterone receptors and to have little or no HER2/neu protein). Because triple-negative breast cancers lack these treatment targets, they are harder to treat and have a poorer prognosis than other types of breast cancer.
If someone has tumor genetic testing that reveals the presence of a harmful change in BRCA1 or BRCA2 in the tumor, they should discuss with their health care provider whether to consider having a germline genetic test to determine if the change was inherited or if it occurred during development of the tumor. Knowing if the change was inherited is important for that individual to understand their risks to potentially develop other cancers in the future. It can also provide an opportunity for family members to learn about their own cancer risks.