Skeletal muscle loss during neoadjuvant chemotherapy as a predictor of major postoperative complications in esophageal cancer patients.

310 Background: Preoperative malnutrition and sarcopenia are known risk factors for postoperative complications. Nutritional therapy and rehabilitation during the perioperative period may help prevent these conditions and contribute to improved postoperative outcomes. Even among patients without pre-treatment sarcopenia, some may experience muscle loss during neoadjuvant chemotherapy (NAC). In this study, we investigated the association between changes in skeletal muscle mass during NAC and postoperative outcomes in non-sarcopenic patients using the Psoas Muscle Index (PMI) as a surrogate marker of nutritional status. Methods: Among 399 patients who underwent esophagectomy for thoracic esophageal squamous cell carcinoma at our institution between 2015 and 2023, 151 received NAC. Of these, 62 patients with pre-NAC sarcopenia were excluded, and the remaining 89 non-sarcopenic patients were retrospectively analyzed. Skeletal muscle mass was assessed by PMI measured at the L3 level on CT. The PMI ratio was defined as the post-NAC PMI expressed as a percentage of the pre-NAC value. Based on time-dependent ROC analysis using overall survival (OS), a cut-off of 90% in PMI ratio was determined, dividing patients into a PMI-decreased group (<90%, n=63) and a PMI-maintained group (≥90%, n=26). Results: The median PMI ratio was 83.1% (IQR: 76.4–90.9). The PMI-decreased group was significantly older than the maintained group (66.1 vs. 61.9 years, P =0.027). No significant differences were observed in NAC regimen, dose reduction, or completion rate. However, grade ≥2 adverse events (CTCAE) were significantly more frequent in the PMI-decreased group (61.9% vs. 38.1%; P =0.018). While there were no significant differences in overall postoperative complication rates (Clavien-Dindo grade ≥II), the incidence of postoperative pneumonia (20.6% vs. 3.9%; P =0.048) and anastomotic leakage (15.9% vs. 0%; P =0.031) was significantly higher in the PMI-decreased group. OS and RFS showed no significant differences, but survival curves tended to favor the PMI-maintained group within the first 3 years. Cox multivariate analysis revealed no significant predictors among patient background factors, PMI change, and perioperative complications. Conclusions: Even among non-sarcopenic patients, a substantial decrease in PMI during NAC was associated with higher incidence of adverse events and postoperative pulmonary and anastomotic complications. Ongoing prospective studies on preoperative nutritional rehabilitation may provide further insights, including our institution’s current efforts.