Utility of metastasis-directed radiotherapy with and without hormonal therapy in management of oligometastatic prostate cancer

Abstract Background Metastasis-directed radiotherapy (MDT) is mainstay in management of oligometastatic prostate cancer (PCa), and PSMA-PET is currently the most sensitive imaging modality for localizing PCa metastases. The efficacy of MDT guided by PSMA-PET imaging with and without androgen deprivation therapy (ADT) +/- androgen-receptor pathway inhibitor (ARPI) has not yet been well characterized. We sought to evaluate the efficacy of PSMA PET-guided MDT. Methods This is a single-institutional retrospective study of patients diagnosed with metastatic PCa by PSMA-PET imaging who were treated with MDT. Survival analyses were performed using the Kaplan-Meier method with Cox proportional hazards testing for significance. Cumulative incidence analyses were performed with Gray’s testing for significance. Results 194 metastatic lesions from 101 patients identified by PSMA PET were irradiated with MDT. 47 of the 79 (59%) patients with hormone-sensitive PCa (HSPC) received ADT +/- ARPI along with MDT. 4 of 194 lesions (2.1%) demonstrated radiographic progression after MDT, with a median follow-up of 22.4 months. 2-year cumulative incidence of progression from HSPC to CRPC was 11% in patients who received ADT +/- ARPI and 35% in those who did not (P = .027). Median biochemical progression free survival of patients with CRPC, HSPC treated without ADT or ARPI, and HSPC treated with ADT +/- ARPI was 5.4, 7.6, and 43.9 months respectively (P .0001). No Grade 3-5 adverse effects were observed. Conclusions MDT guided by PSMA-PET imaging is well-tolerated and delays biochemical progression in patients with CRPC and HSPC, with a greater effect observed in patients also receiving ADT +/- ARPI.