PURPOSE: To identify the approximately 12% with inherited cancer predisposition, all men with metastatic prostate cancer (mPC) should be offered germline genetic testing. This guides treatment choices and impacts cancer prevention in the family. Limited genetic services globally present a barrier to testing. This study tested a potential solution, “mainstreaming,” where counseling and testing are performed by the patient’s oncologist. PATIENTS AND METHODS: Men with mPC at three Australian sites were offered germline genetic testing at their medical oncology appointment. Panel testing ( ATM, BRCA1, BRCA2, BRIP1, CHEK2, EPCAM, FANCA, HOXB13, MLH1, MSH2, MSH6, NBN, PALB2, PMS2, RAD51D, and TP53) was performed on saliva/blood (Invitae, San Francisco, CA). Primary outcomes were clinician and patient satisfaction. Secondary outcomes included mutation rates and resource allocation. RESULTS: Of 66 men offered testing, 63 (95%) accepted. Four pathogenic variants were identified (two BRCA2, one NBN, and one MSH6). Fifty patients and nine clinicians completed questionnaires. Satisfaction was high. All patients were pleased to have had testing overall, 98% (46 of 47) to have had testing at their usual oncology appointment, and all to receive results from their usual specialist, rather than a separate genetics appointment. A total of 88% (7 of 8) of clinicians felt confident, and all were satisfied with mainstreaming. Mainstreaming was resource efficient, requiring 87% fewer genetic consultations than traditional genetic counseling. CONCLUSION: This study demonstrates that mainstreaming of men with mPC is feasible, resource efficient, and satisfactory for clinicians and patients. Widespread implementation as standard of care would facilitate timely access to genetic testing for men with mPC.
