“…All IHC tests, including those for p53 (DO7, prediluted, Dako, Glostrup, Denmark), ARID1A (rabbit polyclonal, 1:2000, Sigma), PMS2 (EP51, prediluted, Dako), and MSH6 (EP49, prediluted, Dako), were performed as described in our previous study. 21 , 22 Furthermore, an IHC test for CTNNB1, the primary antibody of β‐catenin (clone14, 1:500; BD Bioscience), was performed in this study. The term “aberrant p53 staining pattern” refers to either a strong and diffuse nuclear staining pattern (>80% of carcinoma cells) or completely negative (“null pattern”) staining pattern of carcinoma cells, with staining of the adjacent nontumor cells serving as an internal positive control.…”