Epi proColon is an FDA‐approved methylation assay that diagnoses colorectal cancer based on methylation status of the target DNA sequence in the promoter region of the SEPT9. Methylation markers have also been evaluated for early detection of prostate cancer, and a number of studies have shown that tissue‐based GSTP1 methylation assay can achieve relatively high sensitivity (~ 80%) compared with prostate‐specific antigen testing [52, 53]. This evidence concerns the gene GSTP1 and colorectal cancer.