Impact of body fat and muscle quantity on short- and long-term outcome after gastrectomy for cancer.

ABSTRACT

BACKGROUND & AIMS: Preoperative low skeletal muscle mass and obesity have been identified as poor prognostic factors after gastrectomy for cancer, but the predictive value of combined quantitation of skeletal muscle mass and obesity remains unclear. This study examined the impact of combined body compositions on outcomes after gastrectomy for cancer. METHODS: 518 patients who had undergone gastric resection for cancer between 2004 and 2017 were analyzed retrospectively. Skeletal muscle mass (skeletal muscle mass index (SMI)) and visceral obesity (visceral fat area) were measured in preoperative computed tomographic images to categorize patients as outlined below. Impacts of these body compositions on outcomes after gastrectomy were investigated. RESULTS: Body composition was classified as high SMI without obesity in 231 patients (45%), high SMI with obesity in 202 (39%), low SMI without obesity in 55 (11%), and low SMI with obesity in 30 (6%). Postoperative complications developed in 128 patients (25%). Multivariate analysis identified low SMI with obesity as an independent risk factor for postoperative complications (odds ratio, 3.27; P = 0.010). Moreover, patients with low SMI without obesity had lower 5-year overall survival rates than patients with high SMI without obesity (64.4% vs. 88.0%; P < 0.001) and worse 5-year relapse-free survival rates (61.3% vs. 81.3%; P = 0.002). Multivariate analysis identified low SMI without obesity as a significant risk factor for overall survival (hazard ratio, 3.033; P < 0.001) and relapse-free survival (hazard ratio, 2.144; P = 0.008) after gastrectomy. CONCLUSION: Preoperative low SMI with obesity was an independent risk factor for postoperative complications, while low SMI without obesity was an independent risk factor for overall and relapse-free survival following gastrectomy for cancer.