(ChemotherapyAdvisor) – In patients with lung cancer, cigarette smoking alters the expression of many genes in normal lung tissue; many of these changes are irreversible, according to an international team of researchers. This conclusion is based on a study entitled “Molecular Signature of Smoking in Human Lung Tissues,” which was published in Cancer Research on August 1.

In this study, the investigators aimed to identify genes that have their regulation affected by cigarette smoking, especially those genes whose change in expression can be reversed following smoking cessation. To meet these aims, the investigators conducted a large gene expression study on non-tumor lung tissue from 853 patients with lung cancer, the gene expression profiles of which were compared between never smokers and current smokers.

From this large genetic analysis, the investigators found that a total of 3,223 gene transcripts between the two groups had changed their expression (n=344, P<1.29 × 10-6). Smoking induced changes in expression in a large number of genes. Differences in expression of 599 gene transcripts enabled the investigators to clearly differentiate between never smokers and current smokers. The most important finding in the study was a majority of the expression of genes in the current smokers reverted to never-smoker levels following smoking cessation.  

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The investigators concluded that smoking alters the expression of many genes, many of which reverse to normal following smoking cessation. “However, a subset of genes remains altered even decades following smoking cessation and may account, at least in part, for the residual risk of lung cancer among former smokers,” they wrote.