Introduction/Background*TCGA molecular classification for endometrial cancer is expected to propose the most appropriate treatment strategy for each patient. Most of the patients in previous studies on this issue from western countries were treated with adjuvant radiation therapy. Thus, the prognostic stratifications by TCGA molecular classification remain unclear when adjuvant chemotherapy is applied. In this study, we aimed to validate a modified TCGA classification.

Methodology From 2003 to 2015, the patients with endometrial cancer treated in our hospital were enrolled in this retrospective study. The patients who were surgically staged by hysterectomy, bilateral salpingo-oophorectomy, and systematic lymphadenectomy were included, and postoperative adjuvant chemotherapy was applied for the patients at intermediate or high-risk of recurrence. The patients with follow-up period of less than 3 years were excluded. The patients were molecularly classified in combination with conventional recurrent low-risk, and immunohistochemistry (IHC) for PMS2, MSH6 and p53, resulting in four subgroups: low-risk for recurrence by risk classification (Stage IA, Endometrioid carcinoma, Grade 1or2, negative lymph-vascular space invasion), MMRd (PMS2 and/or MSH6 negative), p53abn (p53 positive), and NSMP (none of the above). The 5-year disease-specific survival rates (5y-DSS) were compared among each group.

Result(s)*Total of 175 patients were analyzed. Of 175 patients, 41 patients were classified as low risk for recurrence, 45 patients as MMRd, 19 patients as p53abn, and the remaining 45 patients as NSMP. The median age (58 years old) and follow-up period (104 months) were not significantly different among 4 groups. The distribution of FIGO stage or histological types were also not significantly different except for low-risk group. The 5y-DSS was 100%, 93%, 74%, and 91%, respectively, and the prognosis was stratified into 3 groups: favorable, low-risk for recurrence; intermediate, MMRd and NSMP; unfavorable, p53abn.

Conclusion*We conclude that the prognosis can be stratified by a modified TCGA classification in combination with conventional recurrent risk and IHC for PMS2, MSH6 and p53 in surgically-staged endometrial cancer receiving adjuvant chemotherapy.