Discussion
CRPC, oligometastatic CRPC, hormone-sensitive prostate cancer
METASTATIC TUMORS, METASTATIC CANCER, DISEASE, BONE METASTASIS, METASTASES, HORMONE-SENSITIVE PROSTATE CANCER
We have reported the protocol for a open-label randomized study comparing metastasis-directed therapy ± radium-223 in CRPC patients with metastatic lesions in one to three bones. To the best of our knowledge, this will be the first randomized trial to evaluate the effect of radium-223 in combination with targeted therapy in oligometastatic CRPC patients. Metastatic cancers with three or fewer metastatic sites comprise 30% of CRPC cases; in 35% of these cases, the metastases were confined to bone as assessed by WB-DWI [To date, there is no evidence regarding the efficacy of radiopharmaceutical therapy against oligometastatic CRPC, but the ongoing RAVENS and RROPE trials are evaluating similar treatment strategies in patients with castration-sensitive, hormone-sensitive prostate cancer. The RAVENS trial is a Phase II study evaluating the efficacy of the combination of radium-223 and radiotherapy against active metastases in hormone-sensitive prostate cancer with one to three asymptomatic metastatic tumors of the bone or soft tissue (with at least one bone metastasis), and is scheduled to be completed in August 2024 (NCT04037358) [In CRPC, disease status may not be consistent with PSA changes: the ALSYMPCA study, which showed that radium-223 prolonged overall survival, did not confirm an association between treatment response and PSA changes [Because this is an open-label RCT with unblinded participants and therapists, there is potential for selective bias. Because the primary outcome, radiographic PFS of bone, will be assessed by blinded central radiologists, however, any findings related to the primary outcome will be less prone to assessment bias.