Comparing the nonendometrioid SEOs (n = 18) with the TCGA 2013 serous endometrial carcinoma tumor set (n = 43), molecular profiles were similar except for ARID1A, KRAS, PTEN and TP53. Similar analyses, including only mutations present in both components of each tumor pair, are shown in Supporting Information Table S6. Here, ARID1A is linked to neoplasm.