Simple clinical parameters to identify sarcopenia 1 year after gastrectomy for gastric cancer.

[BACKGROUND] New-onset sarcopenia may develop after gastrectomy even in patients with normal muscle mass, but its detection in routine practice remains challenging. This study evaluated body composition changes after gastrectomy and identified clinical parameters associated with sarcopenia development.

[METHODS] This retrospective study included gastric cancer patients who underwent gastrectomy between 2009 and 2023. Body composition, including body weight (BW), skeletal muscle index (SMI), visceral fat area (VFA), and subcutaneous fat area (SFA), was assessed using CT images obtained preoperatively and 1 year postoperatively. Postoperative sarcopenia was defined as new-onset sarcopenia in patients without preoperative sarcopenia.

[RESULTS] Among 1932 patients, mean percent changes in BW, SMI, VFA, and SFA at 1 year after gastrectomy were - 9.8%, + 1.0%, - 52.8%, and - 34.3%, respectively. Of 1259 preoperative non-sarcopenic patients, 145 (11.5%) developed postoperative sarcopenia and had significantly worse overall survival than those who maintained non-sarcopenia (HR, 2.516; 95% CI, 1.560-4.058; P < 0.001). Among these patients, recurrence incidence in those with stage II or III disease did not differ (Gray's test, P = 0.294), whereas post-recurrence survival was significantly worse in those with postoperative sarcopenia (log-rank, P < 0.001). Four clinical parameters (sex, age ≥ 60, extent of gastrectomy, and BW loss ≥ 8 kg) showed acceptable discrimination for identifying postoperative sarcopenia (simplified risk model; AUROC, 0.792; 95% CI, 0.755-0.829; P < 0.001).

[CONCLUSIONS] New-onset sarcopenia 1 year after gastrectomy was independently associated with poor survival, underscoring its oncologic relevance. Simple clinical parameters may help identify high-risk patients and guide nutritional or exercise interventions.