摘要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),T1 b (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.