The association of genetic testing timing and mutation type on breast cancer management in patients with breast cancer-related mutations

We aim to characterize breast management for patients with genetic mutations and concurrent breast cancer (BC) or prior BC treatment. Adults with a BC-related mutation and prior/concurrent BC diagnosis were identified. Groups were stratified by mutation type [BRCA1/2, high penetrance mutation (HPM), moderate penetrance mutation (MPM)] and timing of genetic testing (concurrent with BC versus after BC treatment). Outcomes were compared. Among 338 patients included, 63 ​% had BRCA1/2 mutations, 9 ​% HPM, and 28 ​% MPM. Approximately 38 ​% had testing concurrent with a BC diagnosis and 62 ​% after BC treatment. Patients with concurrent testing favored bilateral mastectomy (57 ​%) versus 26 ​% lumpectomy, and 16 ​% unilateral mastectomy, which varied by mutation type. Patients previously treated preferred surveillance (92 ​% vs. 8 ​% additional surgery), regardless of mutation type. The timing of a significant BC-related genetic test result and mutation type may be associated with management decisions among patients with breast cancer. •BC patients with concurrent genetic testing favored bilateral mastectomy.•BC patients with subsequent genetic testing favored surveillance.•Management strategies varied based on mutation type/penetrance.