CEACAM5 and cancer: Three circRNAs (circ-CCDC66, circ-ABCC1, and circ-STIL) were significantly downregulated in plasma from patients with colorectal cancer compared to healthy controls, and all of these circRNAs presented higher AUC values than those of commonly used cancer biomarkers, such as CEA and carbohydrate antigen 19–9 (CA19–9) [48].