The review considers the main approaches to the identification of lung cancer (LC) markers, including genetic, epigenetic, protein, transcriptomic, proteomic, metabolic, and miRNA markers. Emphasis is placed on epigenetic markers, which are the most promising because epigenetic changes are among the earliest events in malignant transformation. Special attention is given to circulating tumor markers, which can be detected in easily accessible biological fluids with minimally invasive methods and may be useful for screening the risk groups for LC, diagnosing cancer before its clinical manifestation, monitoring the tumor in remission after therapy, and verifying the diagnosis based on standard clinical and instrumental methods of diagnostics. Extracellular nucleic acids (circulating in blood, circNA) are highlighted as a potential source of material for early diagnosis of LC, prediction of the efficiency of antitumor treatment, posttreatment monitoring, and disease prognosis.