SPINK5 and non-small cell lung carcinoma: Applying univariate Cox regression analysis, 7 genes (LRRC31, HPGD, FCGBP, SPINK5, CYP24A1, S100P and FGG) out of the 20 differentially expressed smoking-related genes were significantly correlated with overall survival (OS) of NSCLC patients with smoking history in GSE50081, GSE68465 and GSE72094 cohort (Fig. 3A).