title: Effect of body mass index on survival of patients with stage I non-small cell lung cancer.
abstract: BACKGROUND
  Body mass index (BMI) has a U-shaped association with lung cancer risk. However, the effect of BMI on prognosis is controversial. This retrospective study aimed to investigate the effect of BMI on the survival of patients with stage I non-small cell lung cancer (NSCLC) after surgical resection.
  
  
  METHODS
  In total, 624 consecutive stage I NSCLC patients who underwent radical resection were classified into four groups according to their BMI: underweight (BMI < 18.5 kg/m2), normal weight (BMI = 18.5-22.4 kg/m2), overweight (BMI = 22.5-28.0 kg/m2), and obese (BMI > 28.0 kg/m2). The effect of BMI on progression-free survival (PFS) and overall survival (OS) was estimated using the Kaplan-Meier method and Cox proportional hazards model. Postoperative complications in each group were analyzed using the Chi square test or Fisher's exact test.
  
  
  RESULTS
  A univariate analysis showed that PFS and OS were longer in the overweight group than in other groups (both P < 0.05). A multivariate analysis showed that OS was longer in the overweight group than in other groups (compared with the other three groups in combination: hazard ratio [HR] = 1.87, 95% confidence interval [CI] 1.30-2.68, P = 0.003; compared with the underweight group: HR = 2.24, 95% CI 1.18-4.25, P = 0.013; compared with the normal weight group: HR = 1.58, 95% CI 1.07-2.33, P = 0.022; compared with the obese group: HR = 2.87, 95% CI 1.48-5.59, P = 0.002), but PFS was similar among the groups (HR = 1.28, 95% CI 0.97-1.68, P = 0.080). A subgroup analysis showed an association between being overweight and prolonged OS in patients at stage T1a (P = 0.024), T1b (P = 0.051), and T2a (P = 0.02), as well as in patients with a non-smoking history (P = 0.001). Overweight patients had lower rates of postoperative complications, such as respiratory failure (compared with the underweight and obese groups: P = 0.014), myocardial infarction (compared with the obese group: P = 0.033), and perioperative death (compared with the other three groups: P = 0.016).
  
  
  CONCLUSIONS
  Preoperative BMI is an independent prognostic factor for stage I NSCLC patients after resection, with overweight patients having a favorable prognosis.
authors.affiliation: Department of Thoracic Surgery, State Key Laboratory of Oncology in Southern China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-Sen University Cancer Center, 651 Dongfeng Rd. East, Guangzhou, 510060, Guangdong, P. R. China.|Lung Cancer Institute, Sun Yat-Sen University, Guangzhou, 510060, Guangdong, P. R. China.
authors.forename: Hao-Jun
authors.initials: HJ
authors.lastname: Xie
authors.affiliation: Department of Thoracic Surgery, State Key Laboratory of Oncology in Southern China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-Sen University Cancer Center, 651 Dongfeng Rd. East, Guangzhou, 510060, Guangdong, P. R. China.|Lung Cancer Institute, Sun Yat-Sen University, Guangzhou, 510060, Guangdong, P. R. China.
authors.forename: Xu
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Department of Thoracic Surgery, State Key Laboratory of Oncology in Southern China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-Sen University Cancer Center, 651 Dongfeng Rd. East, Guangzhou, 510060, Guangdong, P. R. China.|Lung Cancer Institute, Sun Yat-Sen University, Guangzhou, 510060, Guangdong, P. R. China.
authors.forename: Zhen-Qiang
authors.initials: ZQ
authors.lastname: Wei
authors.affiliation: Department of Thoracic Surgery, State Key Laboratory of Oncology in Southern China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-Sen University Cancer Center, 651 Dongfeng Rd. East, Guangzhou, 510060, Guangdong, P. R. China.|Lung Cancer Institute, Sun Yat-Sen University, Guangzhou, 510060, Guangdong, P. R. China.
authors.forename: Hao
authors.initials: H
authors.lastname: Long
authors.affiliation: Department of Thoracic Surgery, State Key Laboratory of Oncology in Southern China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-Sen University Cancer Center, 651 Dongfeng Rd. East, Guangzhou, 510060, Guangdong, P. R. China.|Lung Cancer Institute, Sun Yat-Sen University, Guangzhou, 510060, Guangdong, P. R. China.
authors.forename: Tie-Hua
authors.initials: TH
authors.lastname: Rong
authors.affiliation: Department of Thoracic Surgery, State Key Laboratory of Oncology in Southern China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-Sen University Cancer Center, 651 Dongfeng Rd. East, Guangzhou, 510060, Guangdong, P. R. China. suxd@sysucc.org.cn.|Lung Cancer Institute, Sun Yat-Sen University, Guangzhou, 510060, Guangdong, P. R. China. suxd@sysucc.org.cn.
authors.forename: Xiao-Dong
authors.initials: XD
authors.lastname: Su
mesh_terms: D015992:Body Mass Index; D002289:Carcinoma, Non-Small-Cell Lung / Q000473:pathology / Q000601:surgery*; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000473:pathology / Q000601:surgery*; D008297:Male; D009367:Neoplasm Staging; D009765:Obesity / Q000150:complications*; D050177:Overweight / Q000150:complications*; D011379:Prognosis; D012189:Retrospective Studies; D016019:Survival Analysis
keywords: Body mass index; Early stage; Non-small cell lung cancer; Surgery; Survival