Low Number of Detectable Circulating Tumor Cells in Non-metastatic Colon Cancer

Background: The aim of the present study was to detect circulating tumor cells (CTCs) in the peripheral blood of patients with non-metastatic colon cancer and to evaluate whether there is a diurnal variation in the CTC counts. Furthermore, the study aimed to examine the correlation between CTCs and TNM stage, other paraclinical variables and prognosis. Patients and Methods: Blood samples were collected from 20 consecutive patients with colon cancer TNM stage I-III at four different perioperative time points. Detection of CTCs was performed using the immunological assay CellSearch (R). Results: CTCs were detected in 1 out of 60 preoperative blood samples, resulting in a detection rate of 1 in 20 patients (5%; 95% confidence interval=0.1-25%). None of the postoperative blood samples had CTC levels above the cut-off value (>= 2 CTCs/7.5ml blood). Conclusion: The presence of CTCs in non-metastatic colon cancer is rare and barely detectable with the only commercially available assay for detection of CTCs, the CellSearch System.