Serum microRNA-135a as a diagnostic biomarker in non-small cell lung cancer

The purpose of our research was to evaluate diagnostic performance of serum microRNA-135a (miR-135a) in non-small cell lung cancer (NSCLC). Quantitative real time-polymerase chain reaction was employed to detect the expression serum of miR-135a in NSCLC patients and controls. The influence of serum miR-135a level on clinical characteristics of NSCLC patients was explored through the Chi-square test. Serum carcinoembryonic antigen (CEA) level was estimated via enzyme-linked immunosorbent assay. Receiver operating characteristic (ROC) curve was plotted to elucidate diagnostic roles of serum miR-135a and CEA in NSCLC. The expression level of serum miR-135a was significantly lower in NSCLC patients than in healthy controls (0.40 +/- 0.29 vs 1.00 +/- 0.40, P<.001). Moreover, miR-135a expression was related to lymph node metastasis (P=.021), tumor differentiation (P=.020), and tumor node metastasis stage (P=.031). ROC curve showed serum miR-135a level could discriminate NSCLC patients from healthy controls (P<.0001) with a corresponding cutoff value of 0.665, and a sensitivity and specificity of 81.3% and 83.1%, respectively. The area under the curve was 0.888. In diagnosis analysis on the combination of miR-135a and CEA, when its specificity was maintained at 90%, diagnosis cut-off point reached 0.678. Serum miR-135a level is significantly downregulated in NSCLC and serves as a potential diagnostic biomarker for the disease.