The Cost-Effectiveness of Germline BReast CAncer Gene Testing in Metastatic Prostate Cancer Followed by Cascade Testing of First-Degree Relatives of Mutation Carriers

Objectives: Patients with metastatic prostate cancer (mPCa) with BReast CAncer gene (BRCA) mutations benefit from targeted treatments (eg, olaparib). In addition, family members of affected patients have increased risk of hereditary cancers and benefit from early detection and prevention. International guidelines recommend genetic testing in mPCa; however, the value for money of testing patients with mPCa and cascade testing of blood-related family members has not been assessed. In this context, we evaluated the cost-effectiveness of germline BRCA testing in patients with mPCa followed by cascade testing of first-degree relatives (FDRs) of mutation carriers. Methods: We conducted a cost-utility analysis of germline BRCA testing using 2 scenarios: (1) testing patients with mPCa only and (2) testing patients with mPCa and FDRs of those who test positive. A semi-Markov multi-health-state transition model was constructed using a lifetime time horizon. The analyses were performed from an Australian payer perspective. Decision uncertainty was characterized using probabilistic analyses. Results: Compared with no testing, BRCA testing in mPCa was associated with an incremental cost of AU$3731 and a gain of 0.014 quality-adjusted life-years (QALYs), resulting in an incremental cost-effectiveness ratio of AU$265 942/QALY. Extending testing to FDRs of variant-positive patients resulted in an incremental cost-effectiveness ratio of AU$16 392/QALY. Probability of cost-effectiveness at a willingness-to-pay of AU$75 000/QALY was 0% in the standalone mPCa analysis and 100% in the cascade testing analysis. Conclusion: BRCA testing when performed as a standalone strategy in patients with mPCa may not be cost-effective but demonstrates significant value for money after the inclusion of cascade testing of FDRs of mutation carriers.