The Impact of Preoperative Underweight Status on Postoperative Complication and Survival Outcome of Gastric Cancer Patients: A Systematic Review and Meta-analysis.

Objective: In this study, we performed a systematic review and meta-analysis to evaluate the impact of preoperative underweight status on postoperative complications and survival outcome of gastric cancer (GC) patients.Methods: The related studies were identified by searching PubMed and Embase databases. According to the body mass index (BMI), all patients were classified into underweight group (<18.5kg/m(2)) and normal weight group (18.5kg/m(2), <25kg/m(2)). The relevant data were extracted and pooled effect size were assessed using a fixed effect model or random effect model.Results: A total of 12 studies were included in this meta-analysis. The results indicated that underweight patients had a higher risk of postoperative complications than normal weight patients (RR: 1.28, 95% CI: 1.01-1.61, P < 0.05; I-2 = 57.3%), especially for pulmonary infection (RR: 1.58, 95% CI: 1.03-2.43, P<0.05; I-2 = 47.7%). However, there was no significant difference between underweight and normal weight patients for major surgery-related complications such as anastomotic leakage, wound infection, and intra-abdominal infection. In addition, the short-term (RR: 2.12, 95% CI: 1.47-3.06, P < 0.001; I-2 = 0%) and long-term survival (HR: 1.53, 95% CI: 1.14-2.07, P < 0.01; I-2 = 64.0%) of underweight patients was significantly poorer than that of normal weight patients.Conclusion: Preoperative underweight status was significantly associated with unfavorable postoperative outcome of GC patients. The status may represent excessive nutritional consumption and malnutrition resulting from aggressive tumor.