This was evident both for widespread methylation and at the single gene level (increasing frequencies of methylation from benign to malignant stages) with the exception of HOXA9, MAL, and MGMT. The lack of increase in methylation frequencies between non-malignant adenomas and carcinomas for these three genes may suggest that they are more important in the initiation of cancer, rather than in progression. This evidence concerns the gene MGMT and adenoma.