The most known potential prostate cancer methylation biomarker is glutathione-S-transferase P1 (GSTP1) gene, which encodes an enzyme required for detoxification and protection of DNA from oxidants and electrophilic metabolites. GSTP1 gene methylation status was shown to be able to discriminate between prostate cancer and benign hyperplasia and predict disease recurrence [26, 27]. This evidence concerns the gene GSTP1 and prostate cancer.