Most molecular studies in endometrial cancer have focused on the most common form, uterine endometrioid carcinoma (UEC), which is primarily driven by PTEN loss and mutations in FGFR2, ARID1A, CTNNB1, PIK3CA, PIK2R1, and KRAS [48]. This evidence concerns the gene ARID1A and endometrial endometrioid adenocarcinoma.