In accordance to previous studies, a highly significant increase of GSTP1 promoter methylation was detected in RP-BPH (median 26.6%, range 0.2–65%) and RP-PCa (median 82.5%, range 2.3–99.9%) in comparison to TUR-BPH (median 0.1%, range 0.04–4.9%) (TUR-BPH vs. RP-BPH: p < 0.0001; RP-BPH vs. RP-PCa: p < 0.0001, Mann-Whitney U test) (Fig. 4b). This evidence concerns the gene GSTP1 and benign prostatic hyperplasia.