Abstract IA002: Histopathological classification of endometrial cancers and surrogate markers of genomic subtypes
Authors: Gilks C. Blake 
Published: February 2021

Abstract
Endometrial carcinoma has been subclassified based on tumor cell-type morphology i.e. the resemblance of the tumor cells to their normal counterparts based on microscopic examination. The main histotypes of endometrial carcinoma, endometrioid and serous carcinoma, correspond roughly to Type I and Type II endometrial carcinoma, as described by Bokhman in 1983. Although these histotypes are associated with different patient outcomes and are associated with different mutations, with endometrioid carcinomas having a more favorable prognosis than serous carcinomas, there are a significant number of endometrial carcinomas that are difficult to classify based on histopathological examination. This results in there being only moderate inter-observer reproducibility in the histopathological classification of endometrial carcinoma and this, in turn, compromises the ability to use histotype as a basis for treatment decisions. The Cancer Genome Atlas identified 4 molecular subtypes of endometrial carcinoma based on genomic architecture: ultramutated, hypermutated, low numbers of somatic copy number abnormalities, and high numbers of somatic copy number abnormalities. These correlate with patient outcome and, increasingly, have been show to be correlated with response to treatment. In this presentation the current subclassification of endometrial carcinoma, the development of surrogate markers of genomic molecular subtype and the correlation between molecular subtype and histotype will be discussed,Endometrial carcinoma has been subclassified based on tumor cell-type morphology i.e. the resemblance of the tumor cells to their normal counterparts based on microscopic examination. The main histotypes of endometrial carcinoma, endometrioid and serous carcinoma, correspond roughly to Type I and Type II endometrial carcinoma, as described by Bokhman in 1983. Although these histotypes are associated with different patient outcomes and are associated with different mutations, with endometrioid carcinomas having a more favorable prognosis than serous carcinomas, there are a significant number of endometrial carcinomas that are difficult to classify based on histopathological examination. This results in there being only moderate inter-observer reproducibility in the histopathological classification of endometrial carcinoma and this, in turn, compromises the ability to use histotype as a basis for treatment decisions. The Cancer Genome Atlas identified 4 molecular subtypes of endometrial carcinoma based on genomic architecture: ultramutated, hypermutated, low numbers of somatic copy number abnormalities, and high numbers of somatic copy number abnormalities. These correlate with patient outcome and, increasingly, have been show to be correlated with response to treatment. In this presentation the current subclassification of endometrial carcinoma, the development of surrogate markers of genomic molecular subtype and the correlation between molecular subtype and histotype will be discussed.
Citation Format: C. Blake Gilks. Histopathological classification of endometrial cancers and surrogate markers of genomic subtypes [abstract]. In: Proceedings of the AACR Virtual Special Conference: Endometrial Cancer: New Biology Driving Research and Treatment; 2020 Nov 9-10. Philadelphia (PA): AACR; Clin Cancer Res 2021;27(3_Suppl):Abstract nr IA002.