Clinical characteristics and survival outcomes in veterans receiving radium-223 for metastatic castration-resistant prostate cancer.

Abstract

112 Background: Radium-223 is an alpha-emitting radiopharmaceutical that selectively targets bone metastases while minimizing damage to surrounding tissue. It is approved for the treatment of metastatic castration-resistant prostate cancer (mCRPC), where it improves survival and reduces skeletal-related events. However, the real-world effectiveness of radium-223 and the influence of tumor suppressor gene (TSG) alterations on clinical outcomes remain unclear. Evaluating patient characteristics and survival outcomes in a national veteran population may help identify factors associated with treatment benefit and inform clinical decision-making. Methods: This retrospective cohort study included veterans with mCRPC who initiated radium-223 therapy within the Veterans Health Administration. Demographic and clinical characteristics at treatment initiation included age, BMI, race, PSA within 3 months, and number of radium-223 doses received. Overall survival (OS) was defined from the first radium-223 dose to death, with survivors censored at last follow-up. Kaplan–Meier methods estimated survival outcomes, and subgroup analyses compared OS by TSG alteration status ( PTEN, TP53, RB1 ). Cox regression explored associations between clinical variables and OS. Results: Among 661 veterans, mean age at treatment start was 73 years, mean BMI was 29, and 70% were White, 24% Black, and 6% other race. Each 10-year increase in age was associated with a 19% higher risk of death (HR = 1.19, 95% CI: 1.07–1.31, p =0.001). Race and BMI were not significantly associated with survival. Median baseline PSA was 50 ng/mL (IQR 11–155), and baseline PSA was not significantly associated with survival. Patients received a median of four (IQR 2-6) radium doses, with 38% completing six. Median OS was 11.2 months (95% CI: 10.2–12.1). Among 185 veterans with sequencing data, 49% had PTEN, TP53, or RB1 alterations. OS was similar between TSG-altered (14.2 months) and unaltered (13.1 months) groups. Conclusions: Veterans treated with radium-223 for mCRPC had a median OS of 11.2 months. TSG alterations and baseline PSA were not significantly associated with survival, whereas increasing age was linked to higher mortality risk. Race and BMI showed no significant associations with outcomes. These findings provide real-world benchmarks for radium-223 outcomes in veterans and underscore the need to identify factors that support treatment and optimize survival.