Awareness and Availability of Routine Germline BRCA1/2 Mutation Testing in Patients with Advanced Breast Cancer in Germany

Introduction: Diagnostic testing of germline mutations in breast cancer susceptibility genes 1 or 2 (gBRCA1/2) in patients with human epidermal growth factor receptor 2 negative (HER2-) advanced breast cancer (ABC; locally advanced or metastatic breast cancer) is necessary to assess eligibility for poly(ADP-ribose) polymerase inhibitors (PARPi). We investigated awareness, clinical practice, and the availability of gBRCA1/2 mutation testing in the German outpatient oncology setting. Methods: Office-based oncologists completed a 23-item online survey. Responses were evaluated collectively and by center type. Results: Of 50 oncologists, 33 and 17 were medical and gynecological oncologists, respectively. Oncologists treated a median of 65 (range 14-350) patients with ABC per year. The strongest decision factors to initiate gBRCA1/2 mutation testing were: patient's known family history of gBRCA1/2 mutation-related cancer(s), guideline recommendations, and triple-negative breast cancer (TNBC). In routine practice, 86% of oncologists tested for gBRCA1/2 mutations. Most oncologists (76-98%) reported testing patients with a known family history of gBRCA1/2 mutation-related cancer(s) irrespective of receptor status. For unknown family history, 92% of oncologists reported testing patients with advanced TNBC versus 30% for HR+/HER2- ABC. Oncologists (66%) rated the awareness of therapeutic relevance of gBRCA1/2 mutation testing for targeted treatment selection as good to satisfactory; 22% rated awareness as poor to in-sufficient. Conclusion: Diagnostic gBRCA1/2 mutation testing in patients with HER2- ABC is available and routinely performed in Germany's outpatient oncology setting. However, specific patient subgroups were not routinely tested despite therapeutic indications. Given PARPi availability, opportunities exist to improve testing rates especially for patients with HR+/HER2- ABC without a known family history of gBRCA1/2 mutation-related cancer(s).