GLIM-Defined Malnutrition as a Predictor of Postoperative Morbidity and Survival After Curative Resection for Upper Gastrointestinal Cancer: A Systematic Review and Meta-Analysis.

Background: Malnutrition is common among patients with cancer and has been associated with unfavorable postoperative outcomes, including higher rates of complications. This study aimed to synthesize current evidence on the relationship between malnutrition, as defined by the Global Leadership Initiative on Malnutrition (GLIM) criteria, and postoperative outcomes after curative surgery for upper gastrointestinal (GI) cancers. Methods: We systematically searched the literature from database inception to 28 March 2026. Studies were eligible if they included adult patients with upper GI cancer who underwent surgical resection and had their nutritional status evaluated according to the GLIM criteria. We conducted a systematic review and random-effects meta-analysis. The primary outcomes were overall survival and overall postoperative complications, defined as events with a Clavien-Dindo grade ≥ II occurring within 30 days after surgery. Hazard ratios with 95% confidence intervals for overall survival and risk ratios with 95% CIs for postoperative complications were pooled. Results: Fourteen studies (17 reports) including a total of 7876 patients were eligible for both qualitative and quantitative synthesis. Compared with patients without malnutrition, those with GLIM-defined malnutrition showed poorer overall survival (hazard ratio: 1.96, 95% confidence interval: 1.57-2.45) and a higher risk of postoperative complications (risk ratio: 1.43, 95% confidence interval: 1.14-1.79). Conclusions: GLIM-defined malnutrition was associated with shorter overall survival and a higher incidence of postoperative complications in patients with upper GI cancer after surgery. However, because most included studies were observational and at low-to-moderate certainty of evidence, these associations should be interpreted with appropriate caution.