Detection and evaluation of epithelial cells in the blood of colon cancer patients using RT-PCR

As a mode of colorectal cancer recurrence, liver metastasis plays an important role. One of the factors reported to predict liver metastasis is the detection of trace amounts of tumor cells in the blood. For this purpose, cancer cell-induced cytokeratins (CKs) are generally identified, using the reverse transcriptase-polymerase chain reaction (RT-PCR). In the present study, we aimed to detect trace amounts of tumor cells, based on CK20, in the circulating venous blood, and we examined pathological factors, liver metastasis, and prognosis.

The subjects were 57 colorectal cancer patients who had undergone operation. We examined the cancer-induced marker (CK20) in circulating venous blood by RT-PCR and investigated the relationships between this marker, pathological factors, and prognosis.

Detection ratio of CK20 mRNA was 42.1%, and CK20 was significantly correlated with the pathological factor of lymph node metastasis (P = 0.037). The 5-year survival rate for CK20-positive patients was 62.5% and that for the CK20-negative patients was 87.5%; there was a significant difference (P = 0.048) between the two groups. Recurrence was recognized in six patients; two were positive for CK20 and four were negative for CK20.

These findings indicate that CK20 is strongly related to lymph node metastasis and prognosis, suggesting its usefulness for the diagnosis of colorectal cancer recurrence. However, CK20 did not predict liver metastasis.