Detection of TFPI2 methylation in the serum of colorectal cancer patients.

We examined whether TFPI2 methylation can be used as a molecular marker for colorectal cancers by detecting TFPI2 methylation in colorectal cancer patients' sera by using quantitative methylation-specific polymerase chain reaction (qMSP). The qMSP analysis showed that 39 of 215 (18%) patients exhibited TFPI2 methylation in their serum DNA, suggesting that TFPI2 methylation frequently existed in colorectal cancer patients' sera. After completion of qMSP analysis, clinicopathological data were correlated with molecular data. TFPI2 methylation was significant in the sera of patients with large (p = 0.0022), poorly differentiated carcinoma (p = 0.0164), deep invasion (p = 0.0002), lymph node metastasis (p = 0.0147), or distant metastasis (p < 0.0001). Moreover, TFPI2 methylation was observed more frequently according to the progression of TNM stage, suggesting that serum TFPI2 methylation could be detected more easily in patients with advanced colorectal cancer. We also examined whether serum TFPI2 methylation would be useful in the detection of colorectal cancer, compared to the conventional tumor markers. Detection rates of colorectal cancer using the tumor markers TFPI2 methylation, CEA and CA19-9, in the serum were 18%, 33%, and 17%, respectively. In cases where we combined all three markers, the detection rate was 42%. High sensitivity of qMSP enables detection of smaller amounts of serum tumor DNA. In principle, the methylation status of a primary tumor is not required in advance to detect circulating tumor DNA, suggesting the potential of qMSP as a cancer screening method.