Real-world characteristics and treatment pattern of patients with newly diagnosed endometrial cancer in China.

e17613 Background: Endometrial cancer (EC) is the second most common gynecologic cancer in China with an increasing incidence. Currently, there is no comprehensive profile of EC patients in China. This real-world multicenter retrospective study aimed to depict the characteristics and treatment patterns in newly diagnosed EC patients in China. Methods: Medical records of newly diagnosed EC at 8 hospitals between January 1, 2015 and December 31, 2019 were retrospectively reviewed. The demographic and clinical characteristics at diagnosis as well as the treatment received within 6 months after diagnosis were collected. Results: A total of 1397 patients were enrolled in the study. The average age was 53.5 years. The number of patients (n=1256) classified as stage I, II, III, and IV was 885 (70.5%), 141 (11.2%), 207 (16.5%) and 23 (1.8%), respectively. The number of patients (n=1340) presented with low-grade (G1-2) and high-grade (G3) tumors was 924 (74.0%) and 324 (26.0%), respectively. Invasion of lymphovascular space was detected in 237 (17.0%) out of 1397 patients. Among 1389 patients with pathological data, pure endometrioid carcinoma (90.3%) and serous carcinoma (5.1%) accounted for the majority of pathological types. Estrogen receptor (ER) expression was positive in 91.0% (977/1074) of patients and progesterone-receptor (PR) expression was positive in 85.2% (904/1061) of patients. Mismatch repair deficient/microsatellite instability-high (dMMR/MSI-H) was identified in 26.6% (107/402) of patients. Among 1393 patients with treatment information, surgery was performed in 99.6% of patients and 66.9% received adjuvant treatment following surgery according to clinicopathological risk factors. The percentage of patients receiving adjuvant chemotherapy, adjuvant radiotherapy, and adjuvant chemoradiotherapy was 36.7%, 7.3%, and 22.0%, respectively. Among 306 patients who received chemoradiotherapy, 47.1% underwent concurrent chemoradiotherapy, 31.0% underwent sandwich chemoradiotherapy, and 21.9% underwent sequential chemoradiotherapy. Conclusions: To date, this is the first real-world study with largest sample size of EC patients in China. EC is frequently diagnosed at early 50s in Chinese patients, which is at a younger age compared with European and American population. Newly diagnosed EC patients in China are primarily treated with surgery. Chemotherapy and radiotherapy remain the main adjuvant treatment after surgery. MSI-H/dMMR patients accounted for about 1/4 of newly diagnosed patients, for whom immunotherapy may open up better prognosis in the future.