Comparative Prognostic Impact of Two‐Dimensional and Three‐Dimensional Computed Tomography‐Based Sarcopenia Indices in Metastatic Castration‐Sensitive Prostate Cancer

Objectives This study evaluated and compared the prognostic significance of three different computed tomography (CT)‐based radiological indices of sarcopenia—skeletal muscle index (SMI), psoas muscle index (PMI), and three‐dimensional (3D) psoas muscle volume index (PVI)—in patients with metastatic castration‐sensitive prostate cancer (mCSPC). Methods We retrospectively reviewed 120 patients diagnosed with mCSPC (2003–2022). Baseline muscle parameters were calculated from diagnostic CT scans. Sarcopenia was defined using the Martin criteria for SMI, and optimal cut‐offs derived from maximally selected rank statistics for PMI (4.08 cm 2 /m 2 ) and PVI (92 cm 3 /m 2 ). Associations of these indices with age, overall survival (OS), and prostate cancer‐specific survival (PCSS) were evaluated. Results Advancing age was significantly associated with SMI (OR: 1.05, p = 0.036) and PVI‐defined sarcopenia (OR: 1.09, p < 0.001), with a non‐significant trend for PMI (OR: 1.06, p = 0.069). Survival analysis revealed that sarcopenia by all three indices was significantly associated with worse OS (SMI [HR: 1.88, p = 0.032], PMI [HR: 2.19, p = 0.016], and PVI [HR: 2.07, p = 0.013]). In multivariable analyzes, SMI (HR: 1.86, p = 0.042), PMI (HR: 3.73, p < 0.001), and PVI (HR: 2.46, p = 0.006) remained independent risk factors for poorer OS. No significant impacts were observed for PCSS. Conclusions When using body physique‐adjusted or mathematically optimized thresholds, all three easily and rapidly measurable radiological indices (SMI, PMI, and PVI) may serve as potential, independent prognostic indicators for OS in patients with mCSPC.