[Clinicopathological and molecular genetic features of POLE-mutated endometrioid carcinoma]

Objective: To investigate the clinicopathological and molecular genetic features of POLE mutant endometrioid carcinoma. Methods: Genetic test data of 230 cases of endometrial carcinoma that underwent surgical resection and molecular typing by next generation sequencing in the First Medical Center of Chinese PLA General Hospital from January 2021 to June 2023 were retrospectively analyzed. Seventeen cases of endometrioid carcinoma with POLE mutation were selected. Clinical and prognostic information was collected. The paraffin-embedded tissue and immunohistochemical sections were reviewed, and the gene detection data were analyzed. Results: In the 17 cases of endometrioid carcinoma with POLE mutations, 16 cases (16/230, 6.9%) had mutations at known pathogenic sites, and 1 case had a mutation site (S459Y) that had not been reported, which was inferred to be pathogenic based on clinical prognosis. The 17 patients aged from 48 to 79 years (median 56 years, mean 58 years). All cases had typical histological features of endometrioid carcinoma, including 7 cases (7/17) of poorly-differentiated, 4 cases (4/17) of moderately-differentiated and 6 cases (6/17) of well-differentiated. Squamous differentiation was noted, mucous differentiation was less commonly found and often accompanied by superficial muscle infiltration. The number of stromal lymphocyte infiltration was variable. Lymph-vascular embolus was found in 6 cases, and lymph node metastasis was only detected in 1 case. According to the FIGO staging system for endometrial cancer in 2023, all the cases were in FIGO stage ⅠA_m-POLEmut except for one case in FIGO stage ⅢC1. There were 8 cases with genetic co-mutation, 5 cases with TP53 mutation (immunohistochemically subclonal expression pattern), 1 case with MSI-H, and 2 cases with both TP53 mutation and MSI-H. Five of 7 patients with POLE mutation (poorly-differentiated) received postoperative chemotherapy and/or radiotherapy, 4 patients received endocrine therapy, and 8 patients had no treatment after surgery. One of the stage ⅠA_m-POLEmut tumor patients was found to have pelvic recurrence one year after surgery, and the other 16 patients were followed up for 10-38 months without recurrence or metastasis. Conclusions: POLE mutant endometrioid carcinoma may have different differentiation, and most patients have good prognosis. Correct interpretation of molecular results, accurate identification and classification are important for predicting prognosis and avoiding overtreatment. However, a small number of cases may have recurrence and metastasis, and therefore it is necessary to make a reasonable treatment plan based on the comprehensive judgment of other high risk factors.