GSTP1 and prostate cancer: Indeed, ConfirmMDx (MDxHealth, Irvine, CA, USA), the first commercially available diagnostic methylation test for prostate cancer,14 uses a quantitative methylation specific PCR (qMSP) to measure promoter methylation at GSTP1 (and two additional genes, APC and RASSF1) to detect cancer in histologically negative biopsies.15