Plasma miR-145, miR-20a, miR-21 and miR-223 as novel biomarkers for screening early-stage non-small cell lung cancer

Non‑small cell lung cancer (NSCLC) is the leading cause of cancer‑related mortality in the world. Late diagnosis is one of the most significant reasons for the high mortality rate of lung cancer. The identification of microRNAs (miRNAs) has opened a new field for molecular diagnosis of cancer. The purpose of the present study was to investigate whether plasma miRNAs may be used as biomarkers for early‑stage NSCLC. A total of 232 participants, including 149 NSCLC patients and 83 healthy controls, were recruited between July 2012 and May 2014. We measured the levels of 10 miRNAs (miR‑30d, miR‑383, miR‑20a, miR‑145, miR‑221, miR‑25, miR‑223, miR‑21, miR‑126 and miR‑210) in plasma samples of 40 individuals (20 patients and 20 matched healthy controls) at the point of identification of disease, and 129 NSCLC patients and 83 healthy controls at the validation stage using reverse transcription‑quantitative polymerase chain reaction. Receiver operating characteristics (ROC) curves were generated for each possible combination of the miRNAs. We observed that the expression of plasma miR‑145, miR‑20a, miR‑21 and miR‑223 was significantly increased in the early‑stage NSCLC samples compared with controls. miRNAs have significant diagnostic value for early‑stage NSCLC. Combined ROC analyses using these four miRNAs revealed an elevated area under the ROC curve (AUC) of 0.897, with a sensitivity and specificity of 81.8 and 90.1%, respectively. This AUC helped in distinguishing early‑stage NSCLC. Furthermore, the levels of the four plasma miRNAs were significantly decreased following surgery (P<0.05). Altered expression of miR‑145, miR‑20a, miR‑21 and miR‑223 in plasma are of tumor origin, and the four miRNAs may represent potential novel non‑invasive biomarkers for early‑stage NSCLC.