The current study was undertaken to examine the circulating cancer cells of lung cancer patients using a panel of markers and to evaluate the clinical significance of such tests. Peripheral blood mononuclear cells (PBMCs) from 134 lung cancer patients, 106 benign pulmonary disease, and 80 healthy individuals were isolated and assessed by nested reverse transcription-PCR assay for the expression of three different tumor markers, including tumor specific antigen 9 (TSA-9), Keratin 19 (KRT-19), and Pre-progastrin-releasing peptide (Pre-proGRP). Receiver operating characteristic curve (ROC) analysis showed that the combination of these markers was highly sensitive and specific in differentiating cancer patients from healthy and benign pulmonary disease controls. Of the 134 lung cancer patient blood samples, 84.3% expressed at least one tumor marker. A significant correlation was observed between the number of positive markers and disease stage and progression. Positivity of more than one marker predicted a poor response to therapy and short survival time in non-small cell lung cancer patients.