A retrospective observational study was performed on 83 colorectal adenocarcinoma cases using immunohistochemical evaluation of nuclear β-catenin and H3K27me3 expression in formalin-fixed, paraffin-embedded tumor samples, together with molecular analysis of KRAS, NRAS, and BRAF mutations and microsatellite instability status. This evidence concerns the gene KRAS and colorectal adenocarcinoma.