Evaluation of the reproducibility of the revised 1988 international federation of gynecology and obstetrics grading system of endometrial cancers with special emphasis on nuclear grading

An intraobserver and interobserver analysis of the reproducibility of the revised 1988 International Federation of Gynecology and Obstetrics (FIGO) grading system of endometrial cancers was performed in 47 endometrial cancers (94 biopsy specimens). In the revised FIGO grading system the growth pattern still serves as the basic parameter, but nuclear atypia inappropriate for the architectural grade, raises the grade by 1. Ninety-four slides were graded twice by two pathologists. Analysis by the kappa statistics (corrected for agreement by chance) showed an acceptable result for interobserver reproducibility: kappa value 0.65 (95% confidence interval, 0.480 to 0.818). Further study showed this to be a reflection of the reproducibility of the architectural grade: kappa 0.70 (95% confidence interval, 0.565 to 0.850), whereas the reproducibility of the nuclear grade was poor: kappa value 0.55 (95% confidence interval, 0.383 to 0.713). Review of the literature showed great variability in the definition of nuclear grading, indicating that the revised 1988 FIGO grading system is not applicable as standard of reference for studies of endometrial cancers, before agreeing to the definition of inappropriate nuclear atypia. Cancer 68:2303–2309, 1991.