Genetic testing is widespread among breast cancer patients; however, no guideline recommends using germline genetic testing results to select a chemotherapy regimen. It is unknown whether breast cancer patients who carry pathogenic variants (PVs) in BRCA1/2 or other cancer-associated genes receive different chemotherapy regimens than non-carriers.We linked Surveillance, Epidemiology and End Results (SEER) registry records from Georgia and California to germline genetic testing results from four clinical laboratories. Patients were included who: 1) had stages I-III breast cancer, either hormone receptor-positive and HER2-negative (HR-positive/HER2-negative) or triple-negative (TNBC), diagnosed in 2013-2017; 2) received chemotherapy; and 3) linked to genetic results. Chemotherapy details were extracted from SEER text fields completed by registrars. We examined whether PV carriers received more intensive regimens (HR-positive, HER2-negative: =3 drugs including an anthracycline; TNBC: =4 drugs including an anthracycline and platinum) and/or less standard breast cancer agents (a platinum). All statistical tests were 2-sided.Among 2,293 patients, 1,451 had HR-positive/HER2-negative disease and 842 had TNBC. On multivariable analysis of women with HR-positive/HER2-negative disease, receipt of a more intensive chemotherapy regimen varied significantly by genetic results (p=.02), with platinum receipt more common among BRCA1/2 PV carriers (odds ratio 2.44, 95% confidence interval 1.36-4.38, p<.001). Among women with TNBC, chemotherapy agents did not vary significantly by genetic results.BRCA1/2 PV carriers with HR-positive/HER2-negative breast cancer had two-fold higher odds than non-carriers of receiving a platinum, as part of a more intensive chemotherapy regimen. This likely represents over-treatment and emphasizes the need to monitor how genetic testing results are managed in oncology practice.
View details for DOI 10.1093/jncics/pkac045
View details for PubMedID 35723570