Can microRNAs be utilized as tumor markers for recurrence following nephrectomy in renal cell carcinoma patients? A meta-analysis provides the answer

Renal cell carcinoma (RCC) is an aggressive tumor. Many studies investigated microRNAs (miRs) as RCC prognostic biomarkers, often reporting inconsistent findings. We present a meta-analysis to identify if tissue-derived miRs can be used as a prognostic factor in patients after nephrectomy. Data were obtained from PubMed, Embase, and Web of Science. The hazard ratio with 95% confidence intervals assessed the prognostic value of microRNAs. Outcomes of interest included the prognosis role of microRNAs in overall survival (OS), recurrence-free survival (RFS), and cancer-specific survival (CSS) in nephrectomy patients. Nine retrospective studies that evaluated microRNAs in 1,541 nephrectomy patients were collected. There were heterogeneities across studies for microRNAs in the 15 studies examining OS, RFS, and CSS (I2 = 84.51%; P < 0.01); the random-effect model was calculated (HR = 1.371; (95% CI: 0.831–2.260); P = 0.216). Our study indicated that miRNAs cannot be used as a marker for recurrence in RCC patients after nephrectomy, and researchers shouldn't make the mistake that if miRs can be used as a biomarker in RCC, they cannot be used as a marker after nephrectomy in RCC. As all of these findings were from retrospective studies, further studies are needed to verify the role of microRNAs in clinical trials.