Fourteen of these represented loci that were very frequently and highly methylated: 2C35, CDH13, CDKN2A ex2, CDX2, EYA4, HOXA1, HOXA11, NEUROD1, NEUROD2, OPCML, PTPRN2, SFRP1, TMEFF2 and TWIST1. We added RASSF1 because we had observed that, although its methylation frequency is not as high in adenocarcinoma as some other loci [36], [37], it can be methylated in those adenocarcinomas showing little DNA methylation of the other commonly methylated loci, in other words, its DNA methylation profile can be complementary [36]. This evidence concerns the gene HOXA1 and adenocarcinoma.