Endometrial endometrioid carcinoma, G1, is more aggressive in the elderly than in the young.

AIMS The aim of this study was to characterize endometrioid carcinoma, G1, in the elderly, using clinicopathological features and immunohistochemical features of surrogate markers of molecular subtypes. METHODS AND RESULTS We retrospectively analyzed tumour samples from 268 patients with endometrioid carcinoma, G1 (<40 years: n=24, 40-59 years: n=169, ≥60 years: n=75), for whom long-term clinical follow-up data were available. Endometrioid carcinoma, G1, in the elderly (≥60 years) was characterized by frequent deep myometrial invasion, less frequent endometrioid intraepithelial neoplasia (EIN), lack of benign hyperplasia (BH), less frequent squamous differentiation and occasional aberrant p53 expression. In contrast, this condition in the young (<40 years) was characterized by frequent EIN, BH, and squamous differentiation. Univariate analysis revealed that an elderly status (≥60 years), International Federation of Obstetrics and Gynecology (FIGO) 2009 stage, and aberrant p53 expression were significantly associated with shorter progression-free survival, while multivariate analysis revealed that an elderly status and FIGO 2009 stage were independent poor prognostic factors. CONCLUSIONS Endometrioid carcinoma, G1, in the elderly is more aggressive than that in the young, and an elderly status is an independent predictor of shorter progression-free survival in this condition. We propose that type 1 tumours can be subdivided into types 1a (young onset and indolent) and 1b (old onset and relatively aggressive).