The new 2023 FIGO staging system for endometrial cancer: what is different from the previous 2009 FIGO staging system?

Abstract

OBJECTIVE: The International Federation of Gynecology and Obstetrics committee modified the endometrial cancer (EC) staging system based on the histopathological feature and molecular profile. The aim is to evaluate the clinical implications of the new 2023 system compared with the previous 2009 system. METHODS: We retrospectively identified 161 patients with EC who underwent primary surgical treatment between 2014 and 2018 at Seoul National University Hospital. The droplet-digital polymerase chain reaction for POLE mutations and immunohistochemistry for MLH1, PMS2, MS2, MSH6, and p53 were performed using tissues from formalin-fixed, paraffin-embedded blocks. All patients were categorized according to the 2009 and 2023 staging systems. RESULTS: The median follow-up period was 62.9 months (range, 0.3-110.9), and the median age was 57.2 years old (range, 28.0-85.9). The 5-year progression-free survival (PFS) for the 2023 system with molecular classification was 80.3% for stage I, 75.2% for stage II, 61.2% for stage III, and 22.2% for stage IV (p<0.001). Patients with the 2009 stage I and II disease were restaged using the 2023 system. In contrast, patients with stage III and IV disease were fixed in the 2009 and 2023 systems. Molecular classification downstaged 10 patients (71.4%) to IAmPOLEmut and upstaged 6 patients (37.5%) to IICmp53abn. The 2023 system with molecular classification was associated with PFS and overall survival (p<0.001 and p=0.038). CONCLUSION: The 2023 staging system for EC subdivided stages I and II compared to the 2009 system. The 2023 system with molecular classification is a good predictor of survival.