Prognostic impact of regional lymph node metastasis at castration-resistant prostate cancer diagnosis on survival after radium-223 treatment.

BACKGROUND: Radium-223 (Ra-223) is used for patients with bone-metastatic castration-resistant prostate cancer (CRPC). However, the prognostic value of regional lymph node metastasis at CRPC diagnosis for survival after Ra-223 remains unclear. This study evaluated the association between regional lymph node metastasis at CRPC diagnosis and overall survival (OS) after Ra-223 initiation. METHODS: This multicenter retrospective cohort study used the Following Ra-223 in Outcomes after New-generation Therapy with Investigation of Effects in Refractory prostate cancer study database. Patients with bone-metastatic CRPC who initiated Ra-223 between January 2020 and December 2023 were included. Patients were classified according to the presence or absence of regional lymph node metastasis at CRPC diagnosis. The primary endpoint was OS from Ra-223 initiation. Cox proportional hazards regression was used to evaluate the association between regional lymph node metastasis and OS. RESULTS: Among 802 patients who initiated Ra-223, 718 were included: 505 without regional lymph node metastasis and 213 with regional lymph node metastasis at CRPC diagnosis. Median OS was 31 months (95% confidence interval [CI], 26-35) and 17 months (95% CI, 16-22), respectively (log-rank P < 0.001). In multivariable analysis, regional lymph node metastasis at CRPC diagnosis was associated with poorer OS (hazard ratio, 1.396; 95% CI, 1.092-1.785; P = 0.008). CONCLUSIONS: Regional lymph node metastasis at CRPC diagnosis was associated with poorer OS after Ra-223 initiation. This status may provide prognostic information when considering subsequent treatment sequencing in bone-metastatic CRPC.