Complete Cycles of Radium-223 Improve Overall Survival in Patients With Metastatic Castration-resistant Prostate Cancer: A Retrospective Study

Abstract

Background/Aim: The aim of this study was to investigate whether complete cycles of Radium-223 (Ra-223) improved survival in patients with metastatic castration resistant prostate cancer (mCRPC). Patients and Methods: We retrospectively analyzed mCRPC patients treated with Ra-223 at Taichung Veterans General hospital. Patient and disease characteristics, laboratory results, number of bone metastases, mCRPC treatment sequence, Ra-223 treatment cycles and survival outcomes were collected. Overall survival and progression-free survival (PFS) were analyzed with Kaplan-Meier analysis. Uni- and multivariate analysis was used to identify clinical-radiologic factors that influence outcomes. Results: From October 2016 to December 2020, 42 patients with mCRPC were enrolled. Twenty-three patients received <4 cycles of Ra-223 for mCRPC and 19 patients received 5-6 cycles. The median PSA progression free survival was 2.07 months in the <4 cycles group, compared to 3.93 months in the 5-6 cycles group (log rank p=0.006). The median overall survival was 3.93 months in the <4 cycles group, compared to 28.5 months in the 5-6 cycles group (log rank p<0.001). In the multivariate model, the course number of Ra-223 and pre-treatment alkaline phosphatase (ALP) levels were independent risk factors for overall survival. Conclusion: Patients who complete 5-6 cycles of Ra-223 had significantly better overall survival than those who didn’t. Patients with a lower pre-treatment ALP were more likely to benefit from Ra-223 treatment.