Methylation of TFPI2 No Longer Detected in the Serum DNA of Colorectal Cancer Patients After Curative Surgery

In our previous study, we used quantitative methylation-specific polymerase chain reaction (qMSP) to examine the methylation status of tissue factor pathway inhibitor 2 (TFPI2) in the preoperative serum DNA of 215 colorectal cancer patients and found that TFPI2 was methylated in serum DNA from 39 of these patients. In this study, we examined postoperative serum DNA, obtained within one month after surgery from 38 out of the 39 patients and found that TFPI2 was methylated in the serum DNA of only 18 (47%) of these patients, suggesting that TFPI2 methylation in the serum of the remaining colorectal cancer patients was abolished by surgical tumor reduction. Next, we examined the correlation between the presence of TFPI2 methylation in postoperative serum DNA and residual cancer status after surgery. If R0 (no residual cancer) operations were successfully performed, TFPI2 methylation was not detected in postoperative serum. However, if R2 (obvious residual cancer) operations were performed, 17 (77%) out of 22 postoperative sera, still exhibited TFPI2 methylation. Taken together, our results confirm that detection of methylated TFPI2 in serum DNA was derived from colorectal cancer and could serve as a marker of surgical outcome.