This study also highlighted the different methylation status of SDC2 and TPFI2 between left and right-sided CRCs, which could lead to a detection bias in clinical practice as the right-sided tumors preferred to be detected by methylated SDC2 and the left-sided by methylated TFPI2. Considering that left-sided CRCs are more prevalent in East Asian populations [56–58], the bias may enlarge the risk of CRC being missed when the two markers are applied for different ethnic groups. Here, TFPI2 is linked to colorectal carcinoma.