Impact of timing of radium‑223 administration on the survival of patients with bone metastatic castration‑resistant prostate cancer

The present study aimed to evaluate the optimal timing of radium-223 chloride (Ra-223) administration among patients with bone metastasis from castration-resistant prostate cancer (BmCRPC). Patients, who were diagnosed with BmCRPC and treated with Ra-223 therapy between October, 2016 and January, 2022, were reviewed. The survival time was calculated from the initiation of Ra-223 administration. The time from the diagnosis of BmCRPC to the initiation of Ra-223 administration was identified as a potential prognostic factor. A total of 51 patients were examined in the present study. Ra-223 was administered as the first- and second-line therapy (earlier Ra-223 administration) in 32 patients and as the third- to fifth-line therapy (later Ra-223 administration) in 19 patients. In the multivariate analysis, which considered the potential prognosis, the difference in survival times between patients who received early and late Ra-223 administration was not significant [hazard ratio (HR), 2.67; 95% confidence interval (CI), 0.79-9.07; P=0.11]. By contrast, an incomplete Ra-223 administration (HR, 128.03; 95% CI, 10.59-1548.42; P<0.01) and higher levels of prostate-specific antigen prior to Ra-223 administration (HR, 7.86; 95% CI, 2.7-27.24; P<0.01) were independent factors, significantly associated with a poorer prognosis. The timing of Ra-223 administration did not significantly affect the survival of patients from the initiation of treatment. Further studies are thus required to determine the optimal timing for Ra-223 administration.