Epigenetic diagnostic biomarkers for non-small cell lung cancer: present and future perspectives

Non-small cell lung cancer (NSCLC), of which the main histological types are squamous cell carcinoma (SCC), adenocarcinoma, and large cell carcinoma (LCC), continues to be a major health problem worldwide. Despite several crucial breakthroughs in treatment, the 5-year overall survival rate of NSCLC patients (less than 15%) is still far from satisfactory. The poor prognosis is due in part to the lack of early diagnostic biomarkers. However, progress is being made in this area, particularly with respect to epigenetic markers. Epigenetic regulation of gene expression, which is defined as regulation that occurs without altering the DNA sequence, is involved in the pathology of numerous cancers, including NSCLC. Thus, specific aberrant epigenetic changes are potential biomarkers for the early detection and diagnosis of this disease. In this review, we provide insight into the clinical application of two types of epigenetic regulators: DNA methylation and non-coding RNAs (ncRNAs), both of which play crucial roles in NSCLC tumorigenesis and could be useful diagnostic markers and/or therapeutic targets for NSCLC.