Pancreatic adenocarcinoma is considered one of the most aggressive cancers with high mortality and low 5-year survival rate. This is mainly due to its late detection. Complex anatomical location creates certain difficulties for imaging and puncture biopsy methods, while standard tumor markers do not have high sensitivity and specificity. Thus, the search for specific biomarkers for early diagnosis and prognosis of the disease, as well as monitoring patients with pancreatic cancer during treatment, is a priority to improve patient survival in this terminal disease. Liquid biopsy, which has recently gained a lot of attention including the study of free-circulating tumor DNA (ctDNA) in plasma or serum, is a promising additional method of research. In this review, we will consider the latest findings from the ctDNA study as early and prognostic biomarkers for pancreatic cancer and monitoring the disease during treatment.

By 2004 according to the resuts of the international genome sequencing, about 20,000 protein-coding genes had been analyzed which correspond to more than 2% of the total genomic sequence. The vast majority of gene transcripts are actually characterized as non-coding RNA (ncRNA) and are a cluster of RNA that do not encode functional proteins. They can be small, approximately 20 nucleotides in length, known as microRNAs (miRNAs), or transcripts longer than 200 nucleotides, defined as long non-coding RNAs (lncRNAs). miRNAs are short ncRNAs that are involved in the post-transcriptional regulation of gene expression. Discovered over 15 years ago, these molecules have been recognized as one of the main regulatory molecules in the human genome. They play an important role in all biological processes being important modulators of the eukaryotic genes expression. Focusing on transcripts that encode proteins, miRNAs influence the cellular transcript, thereby helping to determine the outcome of the cell. Aberrant miRNA expression was observed in cancer patients. Tissue concentrations of specific miRNAs have been shown to be associated with tumor invasiveness, metastatic potential, and other clinical characteristics for many types of cancer. Compared to traditional biomarkers like proteins, miRNA has several advantages that will allow them to be considered as new potential biomarkers in cancer. This review looks at biogenesis, functions, technologies used to detect miRNA, and the association of miRNA with human cancer, in particular, colorectal cancer.