Sequencing Life-Prolonging Agents in Castration-Resistant Prostate Cancer Patients: Comparison of Sequences With and Without Radium 223

Background: The retrospective studies that have so far described the outcomes of the sequential use of life-prolonging agents (LPAs) did not include metastatic castration-resistant prostate cancer (mCRPC) patients who received radium 223 (RA223) as part of their treatment. Consequently, it is not known whether including RA223 in the therapeutic sequence has an impact on cumulative survival. The aim of this study was to evaluate this impact by comparing the cumulative overall survival (OS) in two series of mCRPC patients sequentially treated with two or three LPAs after first-line docetaxel (DOC), including RA223 and not. Materials and Methods: The authors retrospectively reviewed the records of mCRPC patients with bone involvement alone who received two or three LPAs (including RA223) after first-line DOC. The control group was a contemporary series of mCRPC patients with bone involvement alone treated with sequences of two or three LPAs other than RA223 after first-line DOC. Results: Median cumulative OS was 40.6 months in the RA223 group of 78 patients and 36.2 months in the non-RA223 group of 186 patients (p = 0.08). OS outcomes were significantly influenced by the number of treatment lines, and baseline Eastern Cooperative Oncology Group performance status (PS) and prostate-specific antigen levels. Conclusions: To the best of the authors' knowledge, this is the first study designed to evaluate the impact of introducing RA223 in the treatment sequences for mCRPC patients, and the results show that its use does not negatively affect cumulative OS.