Sarcopenia Thresholds Derived From Healthy Adult Populations Predict Survival in Patients With Cancer

Introduction Sarcopenia, defined as the loss of skeletal muscle mass and function, is associated with worse postoperative outcomes and reduced survival in patients undergoing surgery for solid tumours, including renal cell carcinoma (RCC). Although radiographic assessment using the skeletal muscle index (SMI) at the L3 vertebral level has emerged as a method for quantifying sarcopenia, a consensus on optimal sarcopenia thresholds, especially in non‐metastatic RCC, remains lacking. This study aims to evaluate which of the existing published SMI thresholds can be utilized to predict overall survival (OS) in a racially diverse non‐metastatic (nmRCC) cohort. Methods We retrospectively reviewed 343 patients with any T‐stage nmRCC who underwent nephrectomy between 2007 and 2022 at our institution. SMI (cm 2 /m 2 ) values were calculated using cross‐sectional imaging at the L3 level. Six published sarcopenia thresholds were applied. Associations between threshold‐defined sarcopenia and OS were evaluated using Kaplan–Meier curves and Cox proportional hazards models adjusted for confounding variables. Results Three hundred forty‐three patients met inclusion criteria, 62.7% were White, and 33.2% were Black. Median follow‐up time was 41.5 months (IQR 17.8–61.7 months), during which there were 62 (18.1%) mortality events. Median SMI measurements for males and females in our cohort were 51.1 and 42.4 cm/m 2 , respectively. Patients defined as radiographically sarcopenic using thresholds by Derstine et al. (HR 2.11 [95% CI 1.14–3.91], p = 0.018) and Tonnesen et al. (HR 2.11 [95% CI 1.15–4.53], p = 0.028) had independently associated worse OS. Notably, these thresholds were constructed from healthy adult populations. Conclusions SMI thresholds derived from healthy cohorts, as proposed by Derstine et al., are associated with OS in patients with nmRCC and may serve as clinically practical tools for identifying high‐risk patients. Incorporating radiographic sarcopenia assessment into preoperative workflows may facilitate targeted prehabilitation interventions aimed at improving survival outcomes in this population.