Urinary microRNAs for prostate cancer diagnosis, prognosis, and treatment response: are we there yet?

Prostate cancer (PCa) remains one of the leading causes of cancer-related deaths in men. Despite the tremendous progress in research over the years, a suitable minimally invasive PCa biomarker is yet to be discovered. The recent advances regarding the roles of microRNAs as biomarkers has allowed for their study in PCa as well, especially as blood-based markers. However, there are several studies that used urine as biological sample to evaluate microRNAs as biomarkers for PCa diagnosis, prognosis, and treatment response, which were reviewed herein. A high degree of inconsistency among reports has been observed, which could be due to several analytical aspects, starting with different urinary fractions used for analysis and continuing with the employment of various analytical platforms and methods of statistical analysis. However, a few microRNAs were found to be dysregulated in the urine of PCa patients, which alone or together with serum prostate-specific antigen seem to improve diagnostic power even in the gray zone of PCa. These results warrant further confirmation by larger prospective studies, preferably using a standardized protocol for analysis. (C) 2017 Wiley Periodicals, Inc.