Abstract:      Background and purpose: It is increasingly focused on that insulin-like growth factor 1 (IGF-1) and insulin-like growth factor binding protein 4 (IGFBP-4) effect cell proliferation, differentiation and apoptosis of tumor cells, and pregnancy-associated plasma protein-A (PAPPA) plays an important role in IGF-1-dependent IGFBP-4 protease mechanism that regulats tumor cells' growth. This study aimed to investigate the serum levels and clinical significance of IGF-1, IGFBP-4, and PAPPA in patients with non-small cell lung cancer (NSCLC). Methods: IGF-1, IGFBP-4, and PAPPA plasma levels were measured by enzyme-linked immunosorbent assay from 82 patients with NSCLC and 40 control subjects, then the correlations between variables were assessed by Spearman correlation analysis, and associations between the IGFs variables and lung cancer risk were calculated through the odds ratio (OR) and its 95% confidence interval (CI) with the use of unconditional logistic regression analysis. Results: Serum levels of IGF-1, IGFBP-4 and PAPPA in NSCLC patients were significantly higher than those in the control group(P<0.05). There was a significant positive correlation between the serum IGF-1 levels and PAPPA levels (r=0.835，P=0.000), and a negative correlation with IGFBP-4 levels (r=-0.612，P=0.000). IGFBP-4 and PAPPA levels were negatively correlated(r=-0.673, P=0.000). High plasma levels of IGF-1(OR=2.28, 95%CI: 1.25-4.36，P=0.008) and PAPPA (OR=1.64, 95%CI: 0.89-3.01，P=0.046)were associated with an increased risk of lung cancer, however high plasma levels of IGFBP-4(OR=0.54, 95%CI: 0.30-1.01，P=0.047)were associated with reduced risk of lung cancer. Conclusion: To detect IGF-1, IGFBP-4 and PAPPA in serum in NSCLC patients is meaningful for the clinical auxiliary diagnosis and biology behavior prediction of NSCLC. And further study of signal transduction pathways of IGFs with the occurrence and development of NSCLC is a meaningful research direction.

Key words: Non-small cell lung cancer, Insulin-like growth factor 1, Insulin-like growth factor binding protein 4, Pregnancy-associated plasma protein-A, Enzyme-linked immunosorbent assay