Correlation Research of Thymidine Synthase Expression in Circulating Tumor Cell and Clinical Characteristics of Colon Cancer.

Objective. To explore the clinical significance of thymidine synthase (TYMS) expression in circulating tumor cells (CTC). Methods. Patients (n=43) were recruited upon reference to the Department of Surgery at a local hospital. Arterial-portal blood samples were harvested from all patients. Patient baseline information was collected when individuals were recruited into the study and include age, sex, and tumor stage. Complete response (CR) events and progressive disease (PD) events were recorded after follow-up. The CTC positive rate and the CTC number were assessed in blood samples. Epithelial-mesenchymal transition (EMT) subgroups and related TYMS expressions were examined for their correlation with colon cancer prognosis. The TYMS expression differed among various EMT subgroups. Results. In our study, the CTC number was not associated with the prognosis index of colon cancer patients. These non-associated indices also include TNM tumor stage, CEA factor, primary tumor position, pathological pattern, age, and sex. However, the total CTC positive rate was correlated with tumor stage. For patients with right colon cancer (10/35), mixed type EMT was in the majority, while epithelial type EMT was the main subgroup in patients with left colon cancer (25/35). The TYMS expression differed among various subgroups of EMT. Left colon cancer (25/35) had the negative expression level of TYMS (75%). Conclusion. CTC positive rate is a promising index for the diagnosis of colon cancer. The lack of TYMS in CTC makes EMT cells prone to becoming epithelial-like cells, and TYMS silence in CTC indicates that the tumor is in the left colon.