Survival benefit of early radium-223 dichloride therapy in castration-resistant prostate cancer patients with osteoblastic bone metastases

The aim of the retrospective cohort study was to evaluate the overall survival of patients with castration-resistant prostate cancer and osteoblastic bone metastases without visceral metastases treated with 223Radium dichloride (223Ra). The cohort included 55 patients aged 48 to 86, with a median age of 71. Overall survival from the first administered cycle (from 7/2015 to 7/2019) was evaluated in 10/2024. The median overall survival was, despite a smaller cohort, 16.27 months (CI: 11.87-20.98 months), comparable to other large real-world studies. Asymptomatic or mildly symptomatic patients with good performance status (ECOG 0-1) at the start of therapy had a significantly higher median survival than more symptomatic patients with ECOG 2 and 3 (22.42 vs. 8.06 and 3.28 months). The number of completed cycles of 223Ra was inversely proportional to the patients' performance status (ECOG) - Kendall's Tau-c = -0.625; p<0.0001. Previous treatment with chemotherapy (41.2 % of patients) was associated with significantly worse survival on multivariable analysis. A decrease of serum PSA by more than 50% (12.7% of patients) was significantly associated with longer survival (31 months; p=0.0043). Severe (Grade 3) anemia, leukopenia, and thrombocytopenia occurred in only 9.1%, 3.6%, and 3.6% of patients. Earlier indication of 223Ra dichloride therapy in asymptomatic or mildly symptomatic patients with good performance status (ECOG 0-1) and without prior chemotherapy improved survival in our cohort. The decrease in serum PSA during treatment was a good prognostic factor associated with longer survival.