Introduction Objective: To validate the revised 2023 International Federation of Gynecology and Obstetrics (FIGO) endometrial cancer staging system, focusingon stage I and II diseases.

Methods Endometrial cancer patients[A1] who received minimally invasive surgery between 2015 and 2017 were enrolled in a retrospective cohort research utilizing the Japan Society of Obstetrics and Gynecology Tumor Registry database. [A2] Stage I disease comprisedIA1 (tumor limited to the endometrium), IA2 (< half ofmyometrial invasion [MI] without LVSI [A3] in non-aggressive tumor), IA3 (low-grade endometrioid tumor limited to the uterus and ovary), and IB (more than half of MI without LVSI in a non-aggressive tumor). Stage II comprisedIIA (stromal invasion), IIB (substantial LVSI), and IIC (aggressive tumor with MI). Multivariable analysis was performed for survival assessment based on cancer stage.

Results In stage I (n=2937), IA2 was not associated with an increased mortality risk rate compared to IA1 (adjusted hazard ratio [aHR], 1.04;95% confidence interval [CI],0.55–[A1] 1.96;P=0.902). IA3 and IB were independently associated with an increased mortality risk (aHR, 3.8; 95%CI, 1.01–14.30;P=0.048; andaHR, 2.39;95%CI, 1.04–5.48;P=0.039, respectively[A2] ) compared to IA1. In stage II (n=696), IIB had a worse, though non-significant, survival rate tendency compared to IIA (aHR,5.35;95%CI,0.74–39.34;P=0.099). IIC was independently associated with an increased mortality rate (aHR, 14.86;95%CI, 2.02–106.8;P=0.008).

Conclusion/Implications The 2023 FIGO staging system for endometrial cancer might be useful to distinguish survival groupsamongstagesIA3, IB, IIA, IIB, and IIC.