The association between skeletal muscle mass index (SMI) and survival after gastrectomy: A systematic review and meta-analysis of cohort studies

Objective: Low skeletal muscle mass index (SMI) is frequently identified in gastric cancer patients but its association with patient survival rate is not clear. This systematic review and meta-analysis aimed to clarify the association between SMI and overall survival in gastric cancer patients after gastrectomy. Methods: PubMed, Scopus, and Web of Science were searched from database inception until July 2021. Studies were eligible if they included gastric cancer patients, measured the SMI level, reported SMI before gastrectomy, defined sarcopenia according to SMI, and had a cohort or case-control design. Primary outcome was cancer survival rate. The risk of bias of individual studies was assessed using the Newcastle – Ottawa Scale. Results: Overall, 22 cohort studies including 7,203 participants were included. The quality of the included studies was moderate to high. A higher overall survival rate was associated with a higher SMI (RR = 1.62, 95% CI: 1.42–1.85). Subgroup analysis suggested a stronger association in overweight or obese patients (RR = 2.39, 95% CI: 1.13–5.09; I2 = 77%; heterogeneity P < 0.01). But no significant differences in the association based on the surgery type (curative surgery vs radical surgery) or the type of gastrectomy (total gastrectomy vs sub-total gastrectomy) were observed. Conclusions: It is suggested that SMI can be a prognostic indicator for overall survival in gastric cancer patients, especially in overweight and obese patients.