To investigated the expression of serum exosomal microRNA-181a-3p (miR-181a-3p) in patients with renal cell carcinoma (RCC) and to evaluate its clinical value as a noninvasive diagnostic marker for RCC.

Seventy-nine RCC patients from Department of Urology and 75 age-sex matched healthy individuals from Health Checkup Center in Nanjing General Hospital between June 2016 and June 2017 were enrolled in this study. Serum exosome were isolated from the patients and healthy individuals, and the levels of exosomal miR-181a-3p were determined by quantitative real-time polymerase chain reaction (qRT-PCR). The clinical value of serum exosomal miR-181a-3p were further assessed by receiver operating characteristic curve (ROC) and logistics analyses.

The relative expression levels of serum exosomal miR-181a-3p in RCC patients [0.264 (0.095-0.782)] were significantly higher than those in healthy individuals [0.068 (0.032-0.130), U=1022, P<0.001]. Moreover, the levels of serum exosomal miR-181a-3p were also significantly higher in early stage RCC patients [0.202 (0.105-0.543)] than those in healthy individuals (U=699, P<0.001). Receive operating characteristic curve (ROC) analysis demonstrated that the area under curve (AUC) for discriminating all RCC patients from healthy individuals was 0.828 (95%CI:0.765-0.890), and when at the optimal cutoff, the sensitivity was 72.2% and the specificity was 72.0%. The AUC for differentiating early stage RCC patients from healthy individuals was 0.837 (95%CI:0.771-0.902), with the sensitivity was 75.4% and the specificity was 72.0% when at the same cutoff. In addition, logistic regression analyses revealed that serum exosomal miR-181a-3p was an independent risk factor of RCC (odds ratio, OR=6.662, 95%CI:3.294-13.474, P<0.001).

Serum exosomal miR-181a-3p levels are significantly increased in RCC patients, especially the early patients, and may be served as a novel non-invasive auxiliary molecular diagnostic marker for RCC.