Emerging circulating MiRNAs and LncRNAs in upper gastrointestinal cancers.

INTRODUCTION: Circulating non-coding RNAs (ncRNAs) possess high stability in circulation, making them capable of being utilized in the diagnosis, prognosis, and treatment of upper gastrointestinal (GI) tract cancers. AREAS COVERED: Herein, the potential clinical application of emerging circulating miRNAs and lncRNAs in upper GI cancers are comprehensively reviewed. EXPERT OPINION: For esophageal cancer (EC), the circulating miRNAs, miR-21, miR-223, and miR-375 have been validated as promising diagnostic biomarkers in a meta-analysis. For gastric cancer (GC), miR-17, miR-18a, miR-21, miR-25, miR-223, miR-451, and lncRNA-H19 have been reported in several studies and are likely to be promising biomarkers. Unlike EC, many circulating lncRNAs have been newly reported for GC and each is often limited to one study. They show excellent or outstanding discrimination performance, such as XIST, LOC100506474, UCA1, LINC00467, ZNFX1-AS1, HULC, AA174084, CEBPA-AS1, MIAT, PCSK2-2:1, HOTTIP, H19 (AUCs 0.8 to 0.9), and particularly CUDR, LSINCT-5, PTENP1, HOTAIR, and LncRNA-GC1 (AUCs > 0.9). Most importantly, using a group of ncRNAs as a diagnostic panel would give a more promising diagnostic or prognostic performance. However, different clinical trials and large, multi-center cohorts as well as comprehensive meta-analyses should also be conducted to validate and use emerging circulating ncRNAs as the indicators of GI cancers.