Background
Approximately 5-17% of prostate cancer cases are linked to heritable mutations and >50% of these are in BRCA genes. Genetic testing to identify BRCA mutations could inform targeted treatments (e.g., olaparib) in men with metastatic prostate cancer (mPCa). Genetic testing of family members of the men who test positive could inform cancer prevention (e.g., mastectomy in female relatives) and early detection (e.g., prostate specific antigen in male relatives). However, the value for money of genetic testing of men with mPCa is unknown.
Aim
To perform an economic evaluation of germline BRCA testing in mPCa followed by cascade testing of first-degree relatives of mutation carriers.
Methods
We conducted a cost-utility analysis of germline BRCA testing in 1) mPCa patients alone 2) mPCa patients and first-degree relatives (FDRs) of the proband and contrasted them with the standard of care without testing. A Markov multistate health transition model was constructed with relevant parameters from the literature and using a lifetime horizon. The analyses were performed from an Australian health payer perspective. Costs and outcomes were discounted at an annual rate of 5%. We set the willingness-to-pay threshold at $AU 75,000/QALY. Decision uncertainty was characterised using probabilistic analyses, and various scenarios were explored.
Results
Compared with no testing, BRCA testing was associated with an incremental cost of AU$ 2,158 and a gain of 0.008 quality-adjusted life years (QALYs), resulting in an incremental cost-effectiveness ratio (ICER) of AU$ 271,473/QALY. The addition of cascade testing of male FDRs yielded an ICER of AU$ 73,866/QALY and the ICER after testing both male and female FDRs was AU$ 10,433/QALY.
Conclusion
This is the first study of the cost-effectiveness of BRCA testing in mPCa. Our results suggest that BRCA testing in mPCa performed as a standalone strategy is not cost-effective but demonstrated significant value for money after the inclusion of cascade testing of first-degree relatives of mutation carriers.