Impact of the FIGO2023 staging system on endometrial cancer in Japan: differences between next-generation sequencing and simplified surrogate marker analysis

BACKGROUND: The International Federation of Gynecology and Obstetrics (FIGO) revised the staging system of endometrial cancer in 2023. In this study, we aimed to determine stage transitions and prognosis of endometrial cancer using FIGO2008, FIGO2023 without molecular classification (FIGO2023), and FIGO2023 with molecular classification (FIGO2023m). METHODS: Eighty-three patients diagnosed with endometrial cancer who underwent surgery and next-generation sequencing (NGS) molecular profiling as part of the Project HOPE cohort study were enrolled. Each case was staged according to the FIGO2008 and FIGO2023 criteria, and we evaluated changes in stage and disease-specific survival (DSS). Molecular classification based on NGS was performed to evaluate FIGO2023m, and the concordance rate with immunohistochemical marker analysis was assessed. RESULTS: Transitioning from FIGO2008 to FIGO2023 resulted in the restaging of 18 cases. Conversely, transitioning from FIGO2008 to FIGO2023m led to the restaging of 15 cases. The concordance rate between FIGO2023 and FIGO2023m staging was 96.4%. With FIGO2023m, the 5-year DSS was 97.6% for stage I (95% confidence interval [CI] 83.9-99.7), 83.3% for stage II (95% CI 56.8-94.3), 100% for stage III (95% CI NA), and 25.0% for stage IV (95% CI 0.9-66.5). Discrepancies in disease staging due to discordance between simplified surrogate marker analysis and NGS evaluation occurred in two cases. CONCLUSIONS: The revision of the staging system from FIGO2008 to FIGO2023 and FIGO2023m resulted in the restaging of several cases, with significant changes between stages I and II.