BACKGROUND
The incidence and number of circulating tumor cells (CTCs) in the peripheral blood of colorectal cancer patients are lower than in other cancer types, which may point to a particular biology of colorectal cancer affecting CTC detection.
METHODS
We detected CTCs in the peripheral and mesenteric blood of colorectal cancer patients by use of 2 independent technologies on the basis of different biological properties of colon cancer cells. Seventy-five patients diagnosed with localized (M0, n = 60) and metastatic (M1, n = 15) colorectal cancer were included. Peripheral and mesenteric blood samples were collected before tumor resection. We performed CTC enumeration with an EpCAM-independent enrichment method followed by the Epispot assay that detected only viable CK19-releasing CTCs. In parallel, we used the FDA-cleared EpCAM-dependent CellSearch® as the reference method.
RESULTS
The enumeration of CK19-releasing cells by the CK19-Epispot assay revealed viable CTCs in 27 of 41 (65.9%) and 41 of 74 (55.4%) (P = 0.04) patients in mesenteric and peripheral blood, respectively, whereas CellSearch detected CTCs in 19 of 34 (55.9%) and 20 of 69 (29.0%) (P = 0.0046) patients. In mesenteric blood, medians of 4 (range 0–247) and 2.7 CTCs (range 0–286) were found with Epispot and CellSearch (P = 0.2), respectively, whereas in peripheral blood, Epispot and CellSearch detected a median of 1.2 (range 0–92) and 0 CTCs (range 0–147) (P = 0.002).
CONCLUSIONS
A considerable portion of viable CTCs detectable by the Epispot assay are trapped in the liver as the first filter organ in CRC patients.
Systematic identification and validation of candidate genes for detection of circulating tumor cells in peripheral blood specimens of colorectal cancer patients