BACKGROUND: The postoperative impact of short-term changes in skeletal muscle loss (SML) and adipose tissue loss (ATL) on treatment outcomes is unclear in patients with gastric cancer (GC). We investigate the role of SML and ATL at 1 month after surgery in determining postoperative survival and recurrence rates in patients with GC. METHODS: We analyzed 540 patients with GC and assessed their skeletal muscle mass, visceral fat mass, and subcutaneous fat mass using computed tomography scans preoperatively and 1 month postoperatively. Patients were categorized into high and low groups based on their levels of SML, visceral ATL (v-ATL), and subcutaneous ATL (s-ATL). Additionally, they were classified into three groups (high ATL, intermediate ATL, and low ATL) based on their v-ATL and s-ATL measurements. RESULTS: Patients with higher v-ATL and s-ATL had lower overall survival (OS) and recurrence-free survival (RFS) rates. High ATL was an independent prognostic factor for decreased OS (hazard ratio [HR] 2.27
95% confidence interval [CI] 1.16-4.42
and P = 0.02) and RFS (HR 2.51
95% CI 1.34-4.71
and P = 0.004) rates. CONCLUSION: A reduction in adipose tissue volume shortly after surgery (1 month) could potentially indicate an increased risk of recurrence and mortality in patients with GC.