Circulating Molecular Biomarkers for the Diagnosis and Monitoring of NSCLC-A Review

Non-small cell lung cancer (NSCLC) is a severe disease with a very poor prognosis. Some 30-80% of patients with NSCLC die within five years of cancer diagnosis. The main factors contributing to this condition are the lack of effective markers for diagnosing cancer at an early stage, as well as the complexity of the biological processes involved in tumorigenesis and progression. The development of knowledge regarding all aspects of NSCLC has provided information used in the detection, systemic anticancer therapy and monitoring of NSCLC, which has a significant impact on prognosis and quality of life. NSCLCs release various biological substances into the bloodstream. Liquid biopsies allow for the analysis of tumor components in body fluids, and the usefulness of these biopsy tests as a substitute for tumor tissue is increasing. In this article, we critically review the available literature on microRNAs, circulating cell-free DNA (cfDNA), tumor-educated platelets (TEPs), circulating tumor cells (CTCs), circulating extracellular vesicles (EVs), and metabolomic and proteomic markers in the diagnosis and monitoring of NSCLC. However, the usefulness of these new markers in clinical practice has significant limitations.