Sarcopenia has been reported to relate to poor prognosis in various malignant cancer types. The present study aimed to clarify the prognostic impact of skeletal muscle mass (SMM) loss after curative gastrectomy in patients with gastric cancer. A total of 119 patients who underwent curative gastrectomy for gastric cancer between 2009 and 2016 were analyzed. The SMM loss at 6 months postoperatively compared with the SMM prior to surgery was calculated using the hospital records. The median loss of SMM was 3.8%. Multivariate logistic regression analysis demonstrated that total gastrectomy was a significant and independent risk factor for SMM loss of ≥5% (odds ratio=2.58
P=0.02). Results from multivariate analysis using stepwise Cox proportional hazards regression indicated that the following factors were significantly associated with shorter overall survival after curative gastrectomy: Age [&gt
70 years
hazard ratio (HR)=2.46, P=0.04], TNM stage (≥2
HR=2.65, P=0.04) and loss of SMM (≥5%
HR=2.57, P=0.03). The present findings suggested that loss of SMM after curative gastrectomy for gastric cancer is an independent predictive factor for poor prognosis.