Serum miR-21 level: a potential diagnostic and prognostic biomarker for non-small cell lung cancer

Because lung cancer is the most common cause of cancer death among both men and women, focused efforts are necessary to identify and develop biomarkers that aid in the detection and treatment of this serious disease. Recent research has been aimed at understanding the roles of microRNAs (miRNAs) in tumorigenesis and their utility as cancer biomarkers. Here, miR-21 was investigated as a potential serum biomarker for non-small cell lung cancer (NSCLC). The relative expression level of miR-21 was detected by real-time PCR in the sera of 80 NSCLC patients; sera were also collected from 60 healthy people as a control. The most suitable cut-off value and the prognostic value of serum miR-21 levels were analyzed using a receiver-operating curve. The relative serum miR-21 level in NSCLC patients was significantly higher than that in healthy people (P<0.05). For relative miR-21 expression, the area under the ROC curve was 0.812 (95% CI: 0.736-0.888) with a sensitivity of 73.8% and a specificity of 71.7%, based on a cut-off value of 1.22. NSCLC patients were divided into two groups based on miR-21 expression; those with higher relative expression (≥1.22) had significantly lower survival time than those in the lower expression group (P<0.05). Further, serum miR-21 level and survival time were negatively correlated in NSCLC patients (P<0.05). Thus, miR-21 may be useful as a diagnostic and prognostic indicator of NSCLC.