Several studies suggested that low-grade, early-stage EECs harboring CTNNB1 exon 3 mutations have worse OS and recurrence-free survival, as also described for MMR deficiency [81,97,98], although their frequent clinic pathological characteristics are commonly associated with lower relapse risk (younger age, squamous differentiation, low TILs, less incidence of deep myometrial invasion, and less incidence of LVSI, with a low number of other concurrent mutations, such as KRAS and FGFR2 mutation). The gene discussed is FGFR2; the disease is mismatch repair cancer syndrome 1.