GSTP1 and prostate intraepithelial neoplasia: Hypermethylation of glutathione S-transferase-pi gene (GSTP1) promoter has been reported to be the most frequent epigenetic modification in PCA and is present in 70% of high-grade prostatic intraepithelial neoplasia (high-grade PIN) lesions and 90% of cancerous tissue samples when compared to normal or benign hyperplastic epithelium [121].