An analysis of two versus three grades for endometrial carcinoma

Introduction. The current grading of uterine endometrioid adenocarcinoma utilizes a three-grade system based on the amount of nonsquamous solid histologic architecture. Of these three grades, we questioned the practical clinical utility of the intermediate grade. Methods. We retrospectively reviewed endometrial biopsy and uterine histology specimens, quantifying the percentage amount of nonsquamous solid tumor by intervals of 10. We then compared these percentage values to other histopathologic prognostic variables. Results. Eighty-five Stage I and II endometrioid adenocarcinoma patients had their preoperative endometrial curettings and operative hysterectomy pathology reviewed independently by two gynecologic pathologists for surgical staging and outcome with a mean follow-up of 6 years. Using a two-tiered system for assessing uterine tumor grade with a delineating value of 20% nonsquamous solid tumor, we found less interobserver variation (kappa = 0.966) compared to the current three-tiered grading system (kappa = 0.526). There were no differences between the two- and three-tiered grading systems regarding myometrial invasion, lymph vascular space invasion, and survival. In the diagnosis of endometrial biopsies, the two-tiered system also improved the prediction of uterine histology grade over the three-tiered system, 90 and 63%, respectively. Conclusion. A two-grade architecture system with a delineation value of 20% would be more reliable and less cumbersome and would have the same or better prognostic significance as the currently used three-grade system.