Gastrointestinal (GI) cancers remain one of the most common malignancies and are the second common cause of cancer deaths
worldwide. The limited effectiveness of therapy for patients with advanced stage and recurrent disease is a reflection of an incomplete
understanding of the molecular basis of GI carcinogenesis. Major advancements have improved our understanding of pathology and
pathogenesis of GI cancers, but high mortality rates, unfavorable prognosis and lack of clinical predictive biomarkers provide an impetus
to investigate new sensitive and specific diagnostic and prognostic markers for GI cancers. MicroRNAs (miRNAs) are short (19-24 nucleotides)
noncoding RNA molecules that regulate gene expression at the posttranscriptional level thus playing an important role in
modulating various biological processes including, but not limited to developmental processes, proliferation, apoptosis, metabolism, differentiation,
epithelial-mechenchymal transition and are involved in the initiation and progression of various human cancers. Unique
miRNA expression profiles have been observed in various cancer types at different stages, suggesting their potential as diagnostic and
prognostic biomarkers. Due to their tumor-specific and tissue-specific expression profiles, stability, robust clinical assays for detection in
serum as well as in formalin-fixed tissue samples, miRNAs have emerged as attractive candidates for diagnostic and prognostic applications.
This review summarizes recent research supporting the utility of miRNAs as novel diagnostic and prognostic tools for GI cancers.