The impact of body mass index on complication and survival in resected oesophageal cancer: a clinical-based cohort and meta-analysis

BACKGROUND: Body mass index (BMI) has been associated with the risk of oesophageal cancer. But the influence of BMI on postoperative complication and prognosis has always been controversial. METHODS: In total, 2031 consecutive patients who underwent oesophagectomy between 1998 and 2008 were classified according to Asian-specific BMI (kg m(−2)) cutoff values. The impact of BMI on overall survival (OS) was estimated using the Kaplan–Meier method and Cox proportional hazard models. We performed a meta-analysis to examine the association of BMI with OS and postoperative complication. RESULTS: Patients with higher BMI had more postoperative complication (P=0.002), such as anastomotic leakage (P=0.016) and cardiovascular diseases (P<0.001), but less incidence of chylous leakage (P=0.010). Logistic regression analysis showed that BMI (P=0.005) was a confounding factor associated with postoperative complication. Multivariate analysis showed that overweight and obese patients had a more favourable survival than normal weight patients (HR (hazard ratio) = 0.80, 95% CI (confidence interval): 0.70–0.92, P=0.001). Subgroup analysis showed that the association with higher BMI and increased OS was observed in patients with oesophageal squamous cell carcinoma (ESCC) (P<0.001), oesophageal adenocarcinoma (EA) (P=0.034), never-smoking (P=0.035), ever-smoking (P=0.035), never alcohol consumption (P=0.005), weight loss (P=0.003) and advanced pathological stage (P<0.001). The meta-analysis further corroborated that higher BMI was associated with increased complication of anastomotic leakage (RR (risk ratio)=1.04, 95% CI: 1.02–1.06, P=0.001), wound infection (RR=1.03, 95% CI: 1.00–1.05, P=0.031) and cardiovascular diseases (RR=1.02, 95% CI: 1.00–1.05, P=0.039), but decreased incidence of chylous leakage (RR=0.98, 95% CI: 0.96–0.99, P<0.001). In addition, high BMI could significantly improved OS (HR=0.78, 95% CI: 0.71–0.85, P<0.001). CONCLUSION: Preoperative BMI was an independent prognostic factor for survival, and strongly associated with postoperative complications in oesophageal cancer.