Abstract: Tumor cell plasticity, including epithelial to mesenchymal transition (EMT) and its reverse program, mesenchymal to epithe-lial transition (MET), regulates circulating tumor cells and carcinoma metastasis. Twist is overexpressed in rhabdomyosarcoma, breast cancer, gastric cancer, and other tumors. Twist, as a transcriptional factor, cross-talks with multiple signaling pathways, forming a com -plex network to participate in the regulation of EMT/MET in circulating tumor cells, which in turn promotes metastasis of tumor cells. Therefore, monitoring the level of Twist and epithelial –mesenchymal phenotypic molecules is important as it may be beneficial for in-creasing the detection ratio of circulating tumor cells as tumor biomarkers and for evaluating the effects of anticancer drugs.