Liquid biopsy in early stage lung cancer

Lung cancer is the leading cause of cancer-associated deaths worldwide. Surgery is the standard treatment for early-stage non-small cell lung cancer (NSCLC). However, 30% to 80% of these patients will die within 5 yearS of diagnosis. Circulating cell-free DNA (cfDNA) harbors pathologic characteristics of the original tumor, such as gene mutations or epigenetic alterations. Analysis of cfDNA has revolutionized the clinical care of advanced lung cancer patients undergoing targeted therapies. However, the low concentration of cfDNA in the blood of early-stage NSCLC patients has hampered its use for management of early disease. Continuing development of more specific and sensitive techniques for detection and analysis of cfDNA will soon enable its leverage in early stage and, perhaps, even screening settings. Therefore, cfDNA analysis may become a tool used for routine NSCLC diagnosis and for monitoring tumor burden, as well as for identifying hidden residual disease. In this review, we will focus on the current evidence of cfDNA in patients with early-stage NSCLC, new and upcoming approaches to identify circulating-tumor biomarkers, their clinical applications and future directions.