Perioperative Immunonutritional Status and Functional Recovery After Gastrectomy for Gastric Cancer: A Prospective Cohort Study of Sex-Related Differences

Background: Gastrectomy for gastric cancer is associated with substantial metabolic, nutritional, and immunological disturbances that may significantly influence postoperative recovery. Increasing evidence suggests that perioperative immunonutritional status, particularly when assessed by the Controlling Nutritional Status (CONUT) score, represents an important predictor of surgical outcomes. However, prospective data evaluating sex-related differences in postoperative nutritional recovery after gastrectomy remain limited. The aim of this study was to evaluate sex-related differences in perioperative immunonutritional status and functional recovery after gastrectomy for gastric cancer using serial CONUT score assessment. Methods: This prospective observational cohort study included 150 consecutive patients undergoing curative-intent gastrectomy for gastric adenocarcinoma at a tertiary referral center between 2021 and 2024. Nutritional and immune status were longitudinally assessed using the CONUT score at predefined perioperative timepoints: preoperatively (T0), early postoperatively (T1), and at 3-month follow-up (T3). Functional recovery outcomes, postoperative complications, and mid-term functional parameters were compared between male and female patients. Multivariable logistic regression analysis was performed to identify independent predictors of delayed postoperative recovery. Results: The study population included 91 male patients (60.7%) and 59 female patients (39.3%). Significant postoperative deterioration in albumin levels, lymphocyte counts, total cholesterol, and CONUT scores were observed in the entire cohort (p-time < 0.001 for all comparisons), followed by partial recovery during follow-up. No significant sex-related differences were identified regarding longitudinal immunonutritional evolution, postoperative complications, gastrointestinal recovery, or functional outcomes (p > 0.05). Overall postoperative complications occurred in 31.3% of patients, while 90-day mortality was 2.7%. An elevated baseline CONUT score ≥ 5 (OR 2.74, 95% CI 1.48–5.09, p = 0.001), postoperative CONUT score T1 ≥ 5 (OR 3.36, 95% CI 1.82–6.19, p < 0.001), ASA class III (OR 2.08, 95% CI 1.19–3.63, p = 0.010), and anastomotic leakage (OR 4.91, 95% CI 1.74–13.88, p = 0.003) independently predicted delayed functional recovery. Male sex was not independently associated with adverse postoperative recovery (OR 1.18, 95% CI 0.74–1.89, p = 0.44). Conclusions: Gastrectomy induces significant postoperative immunonutritional deterioration irrespective of sex. Although biological sex did not independently influence postoperative recovery trajectories, impaired perioperative immunonutritional status—particularly elevated postoperative CONUT score—was strongly associated with delayed functional recovery. Serial perioperative CONUT assessment may represent a valuable tool for individualized postoperative risk stratification and nutritional management in gastric cancer patients undergoing gastrectomy.