Sarcopenia predicts poor long-term survival but not postoperative complications in gastric cancer surgery: an 18-year retrospective cohort study.

INTRODUCTION: Sarcopenia, defined as the loss of skeletal muscle mass and function, is common in gastric cancer (GC) patients and has been associated with adverse outcomes. This study aimed to evaluate the impact of sarcopenia on postoperative complications, mortality, and long-term survival following gastrectomy for GC. METHODS: We conducted a retrospective cohort study of 337 patients who underwent gastrectomy with curative intent at a single tertiary centre between 2000 and 2017. Sarcopenia was defined using CT-based skeletal muscle index at the L3 level, threshold values of ≤ 39 cm²/m² for women and ≤ 55 cm²/m² for men. The primary outcome was overall survival (OS). Postoperative complication burden assessed using the Comprehensive Complication Index (CCI), along with 30- and 90-day mortality and, disease-specific survival (DSS), and disease-free survival (DFS) formed secondary outcomes. RESULTS: Sarcopenia was present in 174 (51.6%) and 163 (48.4%) patients were defined as non-sarcopenic. Complication burden, 30- and 90-day mortality, and DSS/DFS did not differ by sarcopenia status. In the overall cohort, sarcopenia was not independently associated with OS. However, a significant sarcopenia × stage interaction was observed: sarcopenia predicted poorer OS in stage 0-II patients (HR 1.82, 95% CI 1.05-3.17, P = 0.034) but not in stage III-IV disease. CONCLUSIONS: Sarcopenia was not associated with increased postoperative morbidity or short-term mortality, but in stage 0-II GC it was an adverse prognostic factor, conferring an 82% higher risk of death. Routine CT-based assessment may help identify high-risk early-stage patients who could benefit from timely nutritional and physical interventions.