MicroRNAs in Esophageal Cancer: Implications for Diagnosis, Progression, Prognosis and Chemoresistance.

Esophageal cancer (EC), including esophageal squamous cell carcinoma (ESCC) and esophageal adenocarcinoma (EAC), remains a highly lethal disease because of its late diagnosis, significant biological heterogeneity, and frequent resistance to therapy. Growing evidence indicates that microRNAs (miRNAs) are key posttranscriptional regulators involved in tumor initiation, progression, metastasis, and response to treatment. This review provides a comprehensive and updated overview of miRNA dysregulation in both ESCC and EAC, with a specific focus on its emerging clinical relevance in early detection, prognostic assessment, and prediction of therapeutic response. Multiple tissue-based and circulating miRNA signatures, some capable of distinguishing between Barrett's esophagus (BE), dysplasia, and EAC, demonstrate promising diagnostic performance. In parallel, several miRNAs, including miR-21, miR-23a, miR-455-3p, and miR-196b, have been consistently associated with chemoresistance and radioresistance. Moreover, distinct miRNA expression patterns are correlated with tumor aggressiveness, metastatic potential, and the risk of recurrence, supporting their integration with conventional histopathological and molecular parameters for improved patient stratification. Overall, miRNAs represent a powerful class of biomarkers and potential therapeutic targets in EC, with increasing translational relevance in precision oncology.