Decreased expression of miR-204 in plasma is associated with a poor prognosis in patients with non-small cell lung cancer

In order to identify novel non-invasive biomarkers with high accuracy for the screening of non-small cell lung cancer (NSCLC), we investigated the predictive power of 4 microRNAs (miR-146, miR-204, miR-106a and miR-124) in plasma samples obtained from patients with NSCLC and healthy controls (n=50; training phase) by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). We found that the levels of miR-204 in the patients with NSCLC were significantly dysregulated compared with the healthy controls, and thus this miRNA was selected for further validation. For the validation phase, RT-qPCR was performed on plasma samples from patients with NSCLC and healthy controls (n=176) in order to examine the expression levels of the candidate miRNA, miR-204. The results revealed that the plasma levels of miR-204 were significantly downregulated in the patients with NSCLC compared with the healthy controls (p