Clinical outcomes and changes in body composition following endoscopic submucosal dissection versus total gastrectomy in patients with proximal early gastric cancer.

415 Background: Sarcopenia is associated with poor surgical outcomes and prognosis in patients with gastric cancer. However, the relationship between changes in skeletal muscle following endoscopic submucosal dissection (ESD) versus total gastrectomy (TG) in patients with proximal early gastric cancer (EGC) remains unclear. This study aimed to investigate the clinical outcomes and skeletal muscle mass changes between ESD and TG in patients with proximal EGC. Methods: We retrospectively reviewed 329 patients who underwent either ESD (n=127) or TG (n=202) for cT1N0M0 gastric cancer in the upper third of the stomach between 2015 and 2019 at a tertiary care center. The skeletal muscle index (SMI), visceral/subcutaneous fat, and abdominal circumference were measured preoperatively, and at 1 and 3 years after surgery, using cross-sectional computed tomography. We compared these parameters between the two groups and assessed both short- and long-term outcomes, as well as prognostic factors. Results: No significant differences were observed between the two groups with respect to overall survival (P=0.266), recurrence-free survival (P=0.079), or disease-specific survival (P=0.24). The recurrence rate was four (3.1%) in the ESD group and two (0.9%) in the TG group. Of the four recurrences in the ESD group, two were cured by gastrectomy, and two by ESD. Two recurrences in the TG group died of cancer progression. In the ESD group, all deaths were unrelated to gastric cancer, compared to 83.3% in the TG group (P=0.376). Patients in the ESD group showed more preserved SMI (P<0.001), visceral/subcutaneous fat (P<0.001), and abdominal circumference (P<0.001) at 1 and 3 years after surgery, compared to the TG group. The incidence of sarcopenia was significantly lower in the ESD group at postoperative years 1 (22.2% vs. 34.7%, P=0.02) and years 3 (25.7% vs. 40.6%, P=0.001). Sarcopenia had a significant impact on survival, with 5-year OS rates being lower in patients with preoperative sarcopenia (85.3% vs. 95.6%, P=0.005). Multivariate analysis revealed that the prognostic nutritional index was significantly associated with OS (hazard ratio, 0.86; 95% confidence interval: 0.75–0.99, P=0.03). Conclusions: Although OS was comparable between the ESD and TG groups, ESD was associated with better preservation of skeletal muscle and visceral/subcutaneous fat. These results suggest that ESD should be considered for patients with proximal EGC who are at high risk for sarcopenia.