ERBB2 and clear cell adenocarcinoma: HER2 status was also investigated based on EC's distinct variants, which showed positive HER2 expression in 72.1% cases of endometrioid endometrial carcinoma (EEC), 25.5% non-endometrioid endometrial carcinoma (NEC), 50% clear cell carcinoma (CCC), 0% uterine papillary serous carcinoma (UPSC), and 0% squamous carcinoma (SC) (Table 3).