Awareness and Availability of Routine Germline Mutation Testing in Patients with Advanced Breast Cancer in Germany.

Introduction: Diagnostic testing of germline mutations in or (g) 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 g 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 g mutation testing were: patient's known family history of g mutation-related cancer(s), guideline recommendations, and triple-negative breast cancer (TNBC). In routine practice, 86% of oncologists tested for g mutations. Most oncologists (76-98%) reported testing patients with a known family history of g 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 g mutation testing for targeted treatment selection as good to satisfactory; 22% rated awareness as poor to in-sufficient.

Conclusion: Diagnostic g 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 g mutation-related cancer(s).