Radium-223 therapy for metastatic castration-resistant prostate cancer: survival benefit when used earlier in the treatment pathway

Background Radium-223 dichloride (Ra-223) therapy improves overall survival in bony metastatic castration-resistant prostate cancer (mCRPC) patients. Recent guidance change recommends Ra-223 following at least two prior therapies for mCRPC. We evaluated how this change affects overall survival and the optimal timing of Ra-223 in the mCRPC treatment pathway. Methods Retrospective analysis of all mCRPC patients receiving Ra-223 therapy at a single UK centre over a 70-month period. Overall survival, number of prior lines of therapy commenced before Ra-223 initiation and number of Ra-223 therapy cycles completed were identified. Results One hundred ninety-one mCRPC patients received Ra-223 therapy during the study period. One hundred twenty-one (63%) received one prior therapy (group 1) and 70 (37%) received two prior therapies (group 2). Median survival in group 1 was significantly improved, compared to group 2 (448 days vs. 341 days (P = 0.03). Subgroup analysis of 111/191 (58%) patients that completed the recommended six Ra-223 therapy cycles showed additional improved survival. Median survival in group 1 was incrementally significantly improved, compared to group 2 within these patients (665 days vs. 552 days; P = 0.05). There was no difference in the number of patients completing the recommenced six cycles of therapy between the groups [72/121 (59%) vs. 39/70 (56%); P = 0.61]. Conclusion We found a significant survival benefit when Ra-223 was used earlier in the mCRPC treatment pathway, with additional survival advantage seen in those patients completing all six Ra-223 cycles. Our results support the use of Ra-223 earlier in the treatment pathway.

Automated summary

Early use of Ra-223 therapy in mCRPC patients with bone metastases significantly improves overall survival, with additional survival benefit noted in patients who complete all six cycles of therapy. These results support the utilization of Ra-223 earlier in the treatment pathway for mCRPC.