Background:Increased level of serum macrophage inhibitory cytokine-l (MIC-1),a member of transforming growth factor-β superfamily,was found in patients with epithelial tumors.This study aimed to evaluate whether serum level of MIC-l can be a candidate diagnostic and prognostic indicator for early-stage nonsmall cell lung cancer (NSCLC).Methods:A prospective study enrolled 152 patients with Stage Ⅰ-Ⅱ NSCLC,who were followed up after surgical resection.Forty-eight patients with benign pulmonary disease (BPD) and 105 healthy controls were also included in the study.Serum MIC-1 levels were measured using an enzyme-linked immunosorbent assay,and the association with clinical and prognostic features was analyzed.Results:In patients with NSCLC,serum protein levels of MIC-1 were significantly increased compared with healthy controls and BPD patients (all P ＜ 0.001).A threshold of 1000 pg/ml of MIC-1 was found in patients with early-stage (Stage Ⅰ and Ⅱ) NSCLC,with sensitivity and specificity of 70.4％ and 99.0％,respectively.The serum levels ofMIC-1 were associated with age (P =0.001),gender (P =0.030),and T stage (P =0.022).Serum MIC-1 threshold of 1465 pg/ml was found in patients with poor early outcome,with sensitivity and specificity of 72.2％ and 66.1％,respectively.The overall 3-year survival rate of NSCLC patients with high serum levels of MIC-1 (≥1465 pg/ml)was lower than that of NSCLC patients with low serum MIC-1 levels (77.6％ vs.94.8％).Multivariate Cox regression survival analysis showed that a high serum level ofMlC-1 was an independent risk factor for reduced overall survival (hazard ratio =3.37,95％ confidential interval:1.09-10.42,P =0.035).Conclusion:The present study suggested that serum MIC-1 may be a potential diagnostic and prognostic biomarker for patients with early-stage NSCLC.