title: The impact of body mass index on complication and survival in resected oesophageal cancer: a clinical-based cohort and meta-analysis.
abstract: 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).
  
  
  CONCLUSIONS
  Preoperative BMI was an independent prognostic factor for survival, and strongly associated with postoperative complications in oesophageal cancer.
authors.affiliation: 1] Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, People's Republic of China [2] Guangdong Esophageal Cancer Research Institute, Guangzhou, People's Republic of China [3] Department of Thoracic Oncology, Sun Yat-Sen University Cancer Center, Guangzhou, People's Republic of China.
authors.forename: S S
authors.initials: SS
authors.lastname: Zhang
authors.forename: H
authors.initials: H
authors.lastname: Yang
authors.forename: K J
authors.initials: KJ
authors.lastname: Luo
authors.forename: Q Y
authors.initials: QY
authors.lastname: Huang
authors.forename: J Y
authors.initials: JY
authors.lastname: Chen
authors.forename: F
authors.initials: F
authors.lastname: Yang
authors.forename: X L
authors.initials: XL
authors.lastname: Cai
authors.forename: X
authors.initials: X
authors.lastname: Xie
authors.forename: Q W
authors.initials: QW
authors.lastname: Liu
authors.forename: A E
authors.initials: AE
authors.lastname: Bella
authors.forename: R G
authors.initials: RG
authors.lastname: Hu
authors.forename: J
authors.initials: J
authors.lastname: Wen
authors.forename: Y
authors.initials: Y
authors.lastname: Hu
authors.forename: J H
authors.initials: JH
authors.lastname: Fu
mesh_terms: D000230:Adenocarcinoma / Q000175:diagnosis / Q000401:mortality* / Q000601:surgery*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015992:Body Mass Index; D002294:Carcinoma, Squamous Cell / Q000175:diagnosis / Q000401:mortality* / Q000601:surgery*; D002681:China / Q000453:epidemiology; D015331:Cohort Studies; D004938:Esophageal Neoplasms / Q000175:diagnosis / Q000401:mortality* / Q000601:surgery*; D000077277:Esophageal Squamous Cell Carcinoma; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000175:diagnosis / Q000453:epidemiology*; D011379:Prognosis; D016019:Survival Analysis