Smoking correlated with higher expression levels of BRCA1, TYMS and TOP2A and lower expression levels of PDGFRβ. The results were suggestive of correlation between the clinicopathological parameters of the NSCLC patients and the mRNA expression levels of certain lung cancer-related genes, including BRCA1, TYMS, TOP2A, PDGFRβ, VEGFR2, KIT and HER2. This evidence concerns the gene TOP2A and lung cancer.