PTEN and cancer: Of interest, the MSI+ cancers tended to harbour pathogenic mutations in classical colorectal cancer driver genes such as KRAS, ACVR2A, PTEN, BAX and CTNNB1. We found two cancers with mutations (p.Arg298Cys and p.Arg259X) in STAG2, a gene not previously associated with EAC, but known to be a driver gene in other cancer types39; further exploration of TCGA EAC exome data found 6 of 88 tumours with STAG2 mutations (https://tcga-data.nci.nih.gov/tcga/).