Comparison of circulating tumor cells (CTC) and disseminated tumor cells (DTC) in patients with colorectal carcinoma for a predictive marker for tumor recurrence.

Abstract

e14548 Background: Although the presence of CTC or DTC is proposed as a pridictive or a prognostic marker in the management of colorectal carcinoma patients, it is still well unknown what is different of both types of cells. The aim of this study is to compare CTC and DTC as a predictive marker for tumor recurrence by magnetic activated cell sorting system. Methods: Peripheral blood (PB) samples (n=139) and bone marrow (BM) samples (n=41) were preoperatively collected from colorectal carcinoma patients between February 2009 and March 2012. PB samples were obtainable from all patients who provided their BM samples (n=41). Enrichment of CTC was performed by direct immunomagnetic labeling of EpCAM + cells in PB. Enrichment of DTC was done by negative selection of CD45+cells. Subsequently, double immunofluorescences staining for cytokeratin and CD45 was performed to detect CTC or DTC. PB samples from 20 healthy volunteers and BM samples from 3 patients with benign disease were used as controls. Median follow-up time is 28.5 months (range 10-44). Written informed consent was obtained from all enrolled patients. Results: Preoperative positive rates of CTC and DTC were 20.9% (29/139) and 29.3% (12/41), respectively. No CTC or DTC was found in the control groups. In DTC+patients, only 4 patients were positive for CTC (33.3%), whereas 31% of DTC- patients had CTC. We found 13 patients who experienced postoperative recurrence among 139 patients, 7 patients of whom were CTC positive (53.8%). There is a significant higher incidence of recurrence in CTC+patients (risk ratio=4.4, p<0.01). As for DTC, we found 5 patients with recurrence in 41 patients, 4 patients of whom were DTC positive (80%). DTC+ patients have a significant risk of recurrence (risk ratio=9.7, p=0.01). The relationship of CTC / DTC status and the recurrence rates is as follows: 50 % in CTC+/DTC+ patients (2/4); 11.1% in CTC+/DTC- patients (1/9); 25% in CTC-/DTC+ patients (2/8); 0% in CTC-/DTC-patients (0/20). Conclusions: DTC status is more predictive for postoperative recurrence than CTC status. The combination of CTC and DTC analysis might predict recurrence risk more accurately than either of the two analyses.