Cost-effectiveness of upfront therapeutic options in low-volume de novo metastatic hormone-sensitive prostate cancer.

Abstract

211 Background: Low-volume de novo metastatic hormone-sensitive prostate cancer (mHSPC) has historically been treated with lifelong androgen deprivation therapy (ADT). Recently, however, the addition of several advanced therapeutic options – radiation therapy (RT) to the primary, advanced hormonal therapy agents such as abiraterone acetate/prednisone (AAP), and chemotherapy – to ADT have been shown to improve survival in low-volume mHSPC. The objective of this study was to compare the cost-effectiveness of treating low-volume mHSPC patients upfront with RT+ADT, AAP+ADT, or docetaxel+ADT. Methods: A Markov-based cost-effectiveness analysis was constructed comparing three treatment strategies for low-volume mHSPC patients: (1) upfront RT+ADT --> salvage AAP+ADT --> salvage docetaxel+ADT; (2) upfront AAP+ADT --> salvage docetaxel+ADT, and (3) upfront docetaxel+ADT --> salvage AAP+ADT. Transition probabilities were calculated using data from STAMPEDE arms C/G/H, COU-AA-301, COU-AA-302, and TAX-327. RT was delivered via five-fraction stereotactic body radiation therapy. The analysis utilized a 10-year time horizon, and a $100,000/quality adjusted life year (QALY) willingness-to-pay threshold. Utilities were extracted from the literature; costs were taken from Medicare fee schedules and VA oral drug contracts. Results: At 10 years, total cost was $140K, $259K, and $189K, with total QALYs of 4.66, 5.03, and 3.72 for strategies (1) upfront RT+ADT, (2) upfront AAP+ADT, and (3) upfront docetaxel+ADT, respectively. Compared to upfront RT+ADT, upfront AAP+ADT was not cost-effective (ICER: $321K/QALY). This result remained unchanged even after modification of various model inputs in 1-way sensitivity analysis. Upfront docetaxel+ADT was both more costly and less effective than upfront RT+ADT (ICER: -$53K/QALY). Conclusions: At 10 years, RT+ADT is cost-effective compared to other advanced systemic therapy options alone, and should be considered as a viable treatment strategy in all patients with a low-burden of metastatic disease. Additional studies are needed to determine whether any benefit exists in combining RT to the primary with upfront advanced systemic therapy.