THE UTILITY OF THE REVISED ERNATIONAL-FEDERATION-OF-GYNECOLOGY-AND-OBSTETRICS HISTOLOGIC GRADING OF ENDOMETRIAL ADENOCARCINOMA USING A DEFINED NUCLEAR GRADING SYSTEM - A GYNECOLOGIC-ONCOLOGY-GROUP STUDY

Background. The histologic grade of endometrial adenocarcinoma is rela ted to the aggressiveness of the tumor and probability of death from d isease. However, the ideal system for assignment of histologic grade r emains controversial. In 1988, the International Federation of Gynecol ogy and Obstetrics (FIGO) revised its recommendations for grading typi cal endometrial adenocarcinoma, such that grade is determined primaril y by the architecture of the tumor and secondarily modified in the pre sence of ''notable nuclear atypia''; this phrase, however, has never b een defined, and therefore the prognostic validity of this system is u nknown. Methods. Seven hundred and fifteen women with clinical Stage I and occult Stage II endometrial adenocarcinomas (excluding serous or clear cell type) entered on a Gynecologic Oncology Group protocol, and those treated by total abdominal hysterectomy, bilateral salpingo-oop horectomy, and selective pelvic and para-aortic lymph node sampling fo rmed the study population. All cases were centrally reviewed and assig ned an architectural grade and a nuclear grade using specific criteria . The FIGO grade was then determined. The various grading methods were examined based on ability to stratify patients into groups with diffe ring rates of disease progression and relative survival at five years. Results. The architectural grade, nuclear grade, and FIGO grade of tu mors each were used to separate patients into groups with statisticall y significant different rates of progression of disease and relative s urvival. The FIGO modification of architectural grade resulted in the reassignment of 44 patients into a higher grade. The outcome for these 44 was worse than for the remaining patients in the initial grade but was similar to the group into which they were moved. Conclusions. If clearly specified criteria for architectural and nuclear grading are u sed and ''notable nuclear atypia'' is defined as grade 3 nuclei, the 1 988 FIGO grading system has prognostic utility. The authors recommend this system as the standard method for the grading of typical endometr ial adenocarcinoma.