Muscle mass, assessed at diagnosis by L3-CT scan as a prognostic marker of clinical outcomes in patients with gastric cancer: A systematic review and meta-analysis

Background & aims: Computed tomographic (CT) imaging at third lumbar vertebra (L3), routinely used by oncologists, represents a reliable tool to quantify muscle mass. A systematic review and meta-analysis was performed to assess the efficacy of CT scan to define muscle mass as a prognostic marker in gastric cancer (GC) patients undergoing gastrectomy and/or chemotherapy. The primary outcomes were overall survival (OS) and recurrence-free survival (RFS) and the secondary outcomes included postoperative length of hospital stay (P-LOS), total and severe complications in GC patients undergoing gastrectomy. Methods: Three electronic bibliographic databases - MEDLINE, Web of Science and Cochrane Central Register of Controlled Trials - were used to conduct a systematic literature search based on fixed inclusion and exclusion criteria, until April 2019. The adjusted and unadjusted hazard ratio (HR), odds ratio (OR) and mean difference (MD) with 95% confidence interval (CI) were used to analyse the dichotomous variables (OS, RFS, total and severe complications) and continuous variables (P-LOS). Random- and fixed effects models were used according to the heterogeneity. Results: A total of 5610 GC patients from 20 studies were identified. Low muscle mass at diagnosis was found in 32.7% of GC patients and was significantly associated with poorer OS (HR 2.02, 95% CI 1.71-2.38, p < 0.00001, I-2 = 47%) and worse RFS (HR 1.97, 95% CI 1.71-2.26, p < 0.00001, I-2 = 0%). Meta-analysis of adjusted HR from multivariable analyses confirmed the association between OS and low muscle mass (HR 1.89, 95% CI 1.68-2.12, p < 0.00001, I-2 = 36%). Furthermore, low muscle mass and poorer OS were significantly associated in metastatic GC patients exclusively undergoing chemotherapy (HR 1.61, 95% CI 1.23-2.11, p < 0.0006, I-2 = 18%). Moreover, preoperative low muscle mass was significantly associated with longer P-LOS (MD 1.19, 95% CI 0.68-1.71, p < 0.00001, I-2 = 0%), higher risk of postoperative complications (OR 1.76, 95% CI 1.17-2.66, p = 0.007, I-2 = 77%) and severe complications (OR 1.54, 95% CI 1.03-2.29, p = 0.04, I-2 = 49%) in GC patients undergoing gastrectomy. Conclusions: Low muscle mass, assessed by L3 CT-scan, affects almost 1/3 of GC patients at diagnosis and acts as a negative prognostic marker on many clinical outcomes. Therefore, identifying GC patients with low muscle mass at diagnosis or at follow-up visit should be recommendable. Clinical nutritionists should be part of tumor boards meetings to screen low muscle mass in order to prompt personalized nutritional support. (C) 2019 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.