A Binary Grading System for Endometrial Carcinoma Compared with Existing Grading Systems
H Guan, H Arabi, K Hayek, S Bandyopadhyay, L Fathallah, JN Feng, R Ali-Fehmi. WSU, Detroit, MI; St. John Med Center, Detroit, MI
Background: The FIGO grading system is the most widely accepted system for grading endometrial carcinoma, but has been critiqued for poor inter-observer reproducibility. Modified FIGO grading and binary grading systems were proposed in some studies, with encouraging improvement in reproducibility and prognostic power. This study compared prognostic power of a new binary grading system and other existing grading systems.
Design: Between 1995 and 2005, 254 patients underwent hysterectomy for endometrial carcinomas with matched survival information were included in this study. All H and E slides were evaluated by two gynecological pathologists. The morphologic criteria used for our new binary grading system were the presence of predominant solid or papillary architecture pattern, severe nuclear atypia, tumor necrosis and vascular invasion, which were prognostic predictors in univariate analysis (P<0.05). A high grade was assigned to tumors having at least two of these four features, while low grade tumors had at most one. All tumors were also assigned a FIGO grade (I, II, III) and another binary grade using the system described by Alkushi et al. in 2005. The Cox proportional hazards method was used to compare the new grading system and other existing grading system for prognostic significance, controlling for patient age, FIGO stage, and cell type.
Results: Applied to all tumor cell types, the new binary grading system and other tested grading system were independent predictors for survival with similar statistical power (P<0.05). The combination of FIGO grade I and II in the modified binary FIGO grading was an independent predictor but with decreased prognostic power (P value reduced from 0.0048 to 0.0289). When confining multivariate analysis to endometrioid carcinoma only, the new binary grading system showed enhanced predictive power for survival (P = 0.0074), and had more prognostic power than modified FIGO grading system (grades I and II vs.III, P = 0.0289). The traditional FIGO grading system retained its predictive power (P=0.0040), while Alkushi et al. grading system was not statistically significant for predicting survival (P=0.0978).
Conclusions: FIGO grading system demonstrates unequivocal prognostic value for patients with endometrial carcinoma, with additional advantage of being widely accepted by pathologists. The new binary grading system and modified binary FIGO grading systems may offer better reproducibility and ease of use while retaining independent prognostic power.
Monday, March 9, 2009 9:30 AM
Poster Session I Stowell-Orbison/Autopsy Award # 149, Monday Morning