Investigating the biomarker value of circRNAs in the diagnosis of colorectal cancer: a systematic review.

Circular RNAs (circRNAs) has recently been considered a class of endogenous RNAs that form a continuous closed loop with an ability to cancer development. Due to its properties, circRNAs has promising potential to be considered as non-invasive cancer biomarkers. The present review comprehensively and systematically assessed the role of circRNAs as diagnostic markers in blood or tissue samples of colorectal cancer (CRC) patients. Articles published until September 2022 were searched across Scopus, Web of Science (WoS), and PubMed databases to screen and find suitable circRNAs as diagnostic markers in CRC, Based on inclusion and exclusion criteria, 55 articles were selected as the final included articles. The sample size of the patients group ranged from 12 to 212. Among the circRNAs investigated in this study, 47 circRNAs were increased in patients and probably act as oncogenes and activate the downstream pathways in the initiation and exacerbation of cancer; 28 circRNAs were decreased, which probably acted as tumor suppressors and their decrease played a role in the progression of CRC, indicating that the aberrant expression of circRNAs are involved in the promotion of CRC and may associated with its clinicopathological features. Many pathological processes of cancer are regulated by the altered expression of circRNAs through the regulation of different signaling pathways. According to the results of this study, while circRNAs demonstrates promise as a biomarker for CRC diagnosis, it is necessary to conduct evaluative studies on a larger scale in future.