GSTP1 and neoplasm: The frequency of the methylation in tumour tissue was 57.1% in p16, 2.4% in DAP-kinase, 23.8% in GSTP1, 90.5% in APC, 45.2% in RIZ1, 64.3% in SFRP1, 59.5% in SFRP2, 28.6% in SFRP5, 47.6% in RUNX3, and 54.8% in SOCS1, while in MGMT, no aberrant methylation was detected.