Small Foci of Serous Component as a Predictor of Recurrence and Prognosis for Stage IA Endometrial Carcinomas

Objective: Most of the endometrial carcinomas are detected in early stages and have a better prognosis; however, predictive factors for recurrence have not been determined. Methods: Patients with grade 1 endometrioid carcinoma (EG1) according to the 2014 WHO criteria at FIGO 2009 stage IA that were identified through scanning medical charts were included, and we assessed whether the presence of uterine serous carcinoma (SC) component which comprised less than 5% of the total volume using the ovarian two-tiered grading system could be a recurrent risk factor in these patients. Results: Among 126 cases which met inclusion criteria, 12 cases had SC. SC tumors were divided into 2 groups: SC resembling high-grade serous carcinoma (HGSC) and SC resembling low-grade serous carcinoma (LGSC). Five (3.9%) cases had HGSC and 7 (5.6%) cases had LGSC. Recurrence was observed in 3 of all cases (2.3%): 2 cases with HGSC, and 1 case with LGSC. Regarding several clinicopathological factors, only the presence of SC was associated with recurrence. The sensitivity and specificity to predict recurrence using this system were 100 and 93%, respectively. Conclusion: The identification of SC using the ovarian two-tiered grading system could be an accurate predictor of recurrence in stage IA EG1.