GSTP1 and cancer: We found significantly more detectable methylated CpG sites in adjacent non-HCC tissue compared to normal, hepatitis, and cirrhotic liver tissue using BS-PCR sequencing in the 5′ end region (p<0.0001 by Fisher's exact test), suggesting that methylation of the GSTP1 promoter occurs early in the carcinogenetic process that results in HCC and that it plays a role in the cancer microenvironment or field effect.