Serum microRNA-21 is a potential diagnostic marker for earlier lung squamous cell carcinoma detection

High expression of MicroRNA-21 (miR-21) in tumor tissues is associated with shortened survival in patients with lung squamous cell carcinoma (LSCC). This study was to investigate whether serum miR-21 can be used as potential biomarkers for early detection of LSCC. Quantitative reverse transcription-polymerase chain reaction (QRT-PCR) was used to measure the expression of miR-21 in serum of 50 patents with early-stage LSCC, 50 patients with late-stage LSCC (n=50), and 20 patients with pulmonary bullas. The correlation between serum miR-21 expression levels and clinicopathological characteristics of patients was performed. Receiver operating characteristic (ROC) curve was used to assess the serum miR-21 test sensitivity and specificity. Serum levels (RQ Value) of miR-21 were significantly higher in LSCC patients than in patients with pulmonary bulla (P<0.001). MiR-21 was related to TNM stage with higher in late-stage compared to early-stage, but not related age, sex, smoking status. The optimal cutoff values were 2.505 for early-stage LSCC versus pulmonary bulla, 2.570 for late-stage LSCC versus pulmonary bulla, and 4.575 for late-stage LSCC versus early-stage LSCC, and the corresponding sensitivity and specificity was 76.0% and 70.0%, 92.0% and 70.0%, and 78.0% and 78.0%, respectively. Measuring the expression levels of serum miR-21 can serve as a circulating biomarker for the early diagnosis of LSCC.