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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®.


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/7.5 ml 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.