| ---------------------------- 2016 Platform Presentation Winner -------------------------- [1139] Inter-Observer Agreement in Endometrial Carcinoma (EC)
Diagnosis Varies Depending on TCGA Subgroup Assignment
Lien Hoang, Mary A Kinloch, Katherine Grondin, Cheng-Han Lee, Carol Ewanowich,
Martin Kobel, David G Huntsman, Jessica N McAlpine, Robert Soslow, Blake Gilks.
Memorial Sloan Kettering Cancer Center, New York, NY; Saskatoon City Hospital,
Saskatoon, SK, Canada; Laval University, Quebec City, QC, Canada; University of
Edmonton, Edmonton, AB, Canada; University of Calgary, Calgary, AB, Canada; BC
Cancer Agency, Vancouver, BC, Canada; Vancouver General Hospital, Vancouver,
BC, Canada.
Background: We performed molecular analysis on a series of endometrial carcinomas
and stratified them into the same molecular groups as modeled by the Cancer Genome
Atlas (TCGA) (Br J Cancer 2015;113:299-310). Using this series, we examined interobserver
histologic agreement within each of the 4 molecularly defined groups. The
goal was to determine which group is most challenging to diagnose using standard
histologic assessment.
Design: Seven gynecologic subspecialty pathologists based in different tertiary care
centers assigned histologically-based diagnosis given 151 endometrial carcinomas using
1-2 representative slides from hysterectomy specimens. Inter-observer agreement in
histotype diagnosis was then compared between each of the 4 TCGA groups.
Results: Inter-observer agreement in each of the 4 TCGA groups is summarized in
Table 1. Consensus agreement in histotype diagnosis was excellent in the CN-L group,
intermediate in the MSI and POLE, and lowest in the CN-H group.
Table 1. Inter-observer agreement of histologic diagnosis in the 4 molecularly classified
TCGA groups.
| POLE | MSI | CN-L | CN-H | | N | 34 | 40 | 41 | 36 | Consensus
Diagnosis * | 22 (65%) | 23
(58%) | 37 (90%) | 14 (39%) | Histotype
Distribution†
| EC1-2: 19
EC3: 12
SC: 1
CCC: 0
DDEC: 1
Other: 1
| EC1-2: 29
EC3: 7
SC: 0
CCC: 0
DDEC: 2
Other: 2
| EC1-2: 37
EC3: 3
SC: 0
CCC: 0
DDEC: 0
Other: 1
| EC1-2:
4
EC3: 4
SC: 23
CCC: 1
DDEC: 1
Other: 3 |
* All 7 pathologists in agreement
† Kappa values are calculated based on 5 major diagnostic categories: endometrioid,
serous, clear cell, mucinous and other
Conclusions: The degree of diagnostic agreement made by gynecologic subspecialty
pathologists varies depending on TCGA subgroup assignment. In the groups where
inter-observer variability is less optimal (MSI, POLE, CN-H), there may be a role for
ancillary immunohistochemical or molecular studies.
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