APC and colorectal carcinoma: One of the three studies (Xu et al.)reported low frequency of APC methylation in CRC (7.7%) compared to other studies (APC methylation rate arranged from 17.9% to 62.8%), two studies (Dimberg at al. and Michailidi et al.)reported high rate of APC methylation (65.3% and 85.7%) in normal colorectal tissues compared to other studies (APC methylation rate arranged 0-25%).