MLH1 and gastric cancer: As is well known, gastric cancer was categorized into four subtypes according to molecular features by the Cancer Genome Atlas (TCGA) [27, 28, 29]: EBV‐positive subtype with positive EBER; MSI subtype with complete loss of at least one of four MMR protein (MLH1, MSH2, PMS2, and MSH6); genomically stable (GS) subtype with frequent E‐cadherin gene 1 (CDH1) mutation; and chromosome instability (CIN) subtype with frequent TP53 mutation.