However, methylation analysis of non-malignant tissues of 30 patients undergoing curative surgery has shown a much lower frequency of methylation (6.66% for p16 and 13.33% for DAPK, 16.66% for GSTP1 and 0% for BRCA1) as compared to their corresponding tumour tissues (46.7%, 63.3%, 63.3% and 20% for p16, DAPK, GSTP1 and BRCA1 respectively) shown in Figure S1. Here, GSTP1 is linked to neoplasm.