ARID1A and adenocarcinoma: The cohort consisted of 178 EEC, grade 1 (EEC1, 61.0%), 40 EEC, grade 2 (EEC2, 13.7%), 26 EEC, grade 3 (EEC3, 8.9%), 15 ESC (5.1%), 12 CS (4.1%), 9 ECCC (3.1%), 9 DDEC (3.1%; 8/9 were SWI/SNF‐deficient, all with ARID1B/ARID1A co‐loss), and one each of mesonephric‐like adenocarcinoma, large cell neuroendocrine carcinoma, and squamous cell carcinoma.