C1GALT1C1 and cancer: Recently, hypermethylation in Cosmc, which would result in Cosmc gene silencing, was reported in pancreatic tumours and Tn syndrome expressing truncated O‐glycans.26, 35 We therefore conducted a MALDI‐TOF spectrometry methylation analysis of Cosmc and T‐synthase in another pair of Tn‐positive and Tn‐negative cancer tissues.