Prognosis and Reproducibility of New and Existing Binary Grading Systems for Endometrial Carcinoma Compared to FIGO Grading in Hysterectomy Specimens

Background: The current International Federation of Gynecology and Obstetrics (FIGO) grade in endometrial carcinomas requires the evaluation of histologic features with proven prognostic value but with questionable reproducibility. This study tests the prognostic power and reproducibility of a new binary grading system. Study Design: Specimens from 254 hysterectomies were graded according to the new 3- and 2-tiered FIGO grading systems described by Alkushi et al. The selected morphologic parameters for the new grading system included the presence of predominant solid or papillary architecture pattern, severe nuclear atypia, tumor necrosis, and vascular invasion. The Cox proportional hazards and kappa statistics were used for comparisons. Results: On multivariate analysis, and looking at all tumor cell types, the 4 tested grading systems were independent predictors of survival, with the 3-tiered FIGO grading system being the most predictive (P = 0.005). In the subset of endometrioid tumors, the 3- and 2-tiered FIGO grading systems and the new grading system retained their statistical significance as predictors of survival (P = 0.004, P = 0.03, and P = 0.007, respectively), whereas the grading system of Alkushi et al did not (P = 0.1). In nonendometrioid tumors, the new grading system proved to be the best predictor of survival, reaching near statistical significance (P = 0.06). The new grading system had acceptable intraobserver and interobserver reproducibility assessment (kappa = 0.87 and kappa = 0.45, respectively). Conclusion: The 3-tiered FIGO grading system retained its superior prognostic power. However, available binary grading systems remain an attractive option by being highly reproducible and by eliminating the clinical ambiguity of intermediate grades of disease.