Objective: We propose a new staging system for stage I endometrial cancer and compare its performance to the 1988 and 2009 International Federation of Gynecology and Obstetrics (FIGO) systems.
Methods: We analyzed patients with 1988 FIGO stage I endometrial cancer from January 1993 to August 2011. Low-grade carcinoma consisted of endometrioid grade 1 to grade 2 lesions. High-grade carcinoma consisted of endometrioid grade 3 or nonendometrioid carcinomas (serous, clear cell, and carcinosarcoma). The proposed system is as follows:
IA. Low-grade carcinoma with less than half myometrial invasion
IA1: Negative nodes
IA2: No nodes removed
IB. High-grade carcinoma with no myometrial invasion
IB1: Negative nodes
IB2: No nodes removed
IC. Low-grade carcinoma with half or greater myometrial invasion
IC1: Negative nodes
IC2: No nodes removed
ID. High-grade carcinoma with any myometrial invasion
ID1: Negative nodes
ID2: No nodes removed
Results: Data from 1843 patients were analyzed. When patients were restaged with our proposed system, the 5-year overall survival significantly differed (P < 0.001): IA1, 96.7%; IA2, 92.2%; IB1, 92.2%; IB2, 76.4%; IC1, 83.9%; IC2, 78.6%; ID1, 81.1%; and ID2, 68.8%. The bootstrap-corrected concordance probability estimate for the proposed system was 0.627 (95% confidence interval, 0.590–0.664) and was superior to the concordance probability estimate of 0.530 (95% confidence interval, 0.516–0.544) for the 2009 FIGO system.
Conclusions: By incorporating histological subtype, grade, myometrial invasion, and whether lymph nodes were removed, our proposed system for stage I endometrial cancer has a superior predictive ability over the 2009 FIGO staging system and provides a novel binary grading system (low-grade including endometrioid grade 1–2 lesions; high-grade carcinoma consisting of endometrioid grade 3 carcinomas and nonendometrioid carcinomas).
*Gynecology Service, Department of Surgery, †Department of Pathology, and ‡Department of Epidemiology and Biostatistics, Memorial Sloan-Kettering Cancer Center, New York, NY; §Weill Cornell Medical College, New York, NY; ∥Gynecologic Medical Oncology Service, Department of Medicine, Memorial Sloan-Kettering Cancer Center, New York, NY; and ¶Department of Pathology and Molecular Genetics and Research Laboratory, Hospital Universitari Arnau de Vilanova, University of Lleida, IRBLLEIDA, Lleida, Spain.
Address correspondence and reprint requests to Robert A. Soslow, MD, Department of Pathology, Memorial Sloan-Kettering Cancer Center, 1275 York Ave, New York, NY. E-mail: firstname.lastname@example.org.
This work was supported in part by the National Institutes of Health Cancer Center core grant (P30 CA008748). The core grant provides funding to institutional cores, such as Biostatistics and Pathology, which were used in this study.
The authors declare no conflicts of interest.
Joyce N. Barlin and Robert A. Soslow are co–first authors.
Received June 5, 2013
Accepted July 14, 2013