When the data were analyzed on the basis of age, gender and smoking history, the results showed that the mean serum concentration of IGFBP2 in lung cancer patients was significantly higher than that in healthy and benign participants (P < 0.001) (Fig. 1A); however, the expressions of IGFBP2 between healthy and benign participants were not significant. Here, IGFBP2 is linked to lung carcinoma.