ABCG2 and rectum adenocarcinoma: While ABCG2 promoter hypomethylation was noted in both adenocarcinomas and normal samples (beta values range 0.033–0.090), slightly, but significantly, lower methylation was found for both colon (p < 0.01) and rectum adenocarcinomas (p = 0.0247) in comparison to normal samples.