Optimal Cutoff Values of Skeletal Muscle Index to Define Sarcopenia for Prediction of Survival in Patients with Advanced Gastric Cancer

Abstract

Background: Sarcopenia, characterized by loss of skeletal muscle mass, is recognized as a prognostic factor in patients with gastric cancer. However, wide variability exists in the cutoff values of muscle mass for defining sarcopenia across previous studies, and the best cutoff values to predict survival remain unknown. This study aimed to determine the optimal cutoff values for sarcopenia to predict survival in patients with advanced gastric cancer. Patients and Methods: Patients with clinical stage II/III gastric cancer who underwent gastrectomy at Kyoto University Hospital were included in the study. The cross-sectional area of skeletal muscle at the third lumbar vertebra level was measured using preoperative computed tomography scan. The skeletal muscle index (SMI) was calculated by dividing the area by height in meters squared. Five sex-specific cutoffs of SMI, which were significantly associated with prognosis in patients with gastric and nongastric cancers, were examined as a threshold to define sarcopenia. Results: In the 177 eligible patients, the five cutoffs of SMI resulted in an incidence of sarcopenia between 6 (3%) and 114 (64%). The 5-year overall survival was 48% in patients with sarcopenia based on the cutoffs reported by Martin et al., compared with 68% in those without sarcopenia (p = 0.013). A multivariate regression model demonstrated that sarcopenia based on the cutoffs was significantly associated with overall survival (hazard ratio 2.00, 95% confidence interval 1.24–3.24, p = 0.005). Conclusions: The cutoff values reported by Martin et al. were optimal to predict survival in patients with advanced gastric cancer.