Histologic grading of breast carcinoma: A multi-institution study of interobserver variation using virtual microscopy Journal Article

Authors: Ginter, P. S.; Idress, R.; D'Alfonso, T. M.; Fineberg, S.; Jaffer, S.; Sattar, A. K.; Chagpar, A.; Wilson, P.; Harigopal, M.
Article Title: Histologic grading of breast carcinoma: A multi-institution study of interobserver variation using virtual microscopy
Abstract: Breast carcinoma grading is an important prognostic feature recently incorporated into the AJCC Cancer Staging Manual. There is increased interest in applying virtual microscopy (VM) using digital whole slide imaging (WSI) more broadly. Little is known regarding concordance in grading using VM and how such variability might affect AJCC prognostic staging (PS). We evaluated interobserver variability amongst a multi-institutional group of breast pathologists using digital WSI and how discrepancies in grading would affect PS. A digitally scanned slide from 143 invasive carcinomas was independently reviewed by 6 pathologists and assigned grades based on established criteria for tubule formation (TF), nuclear pleomorphism (NP), and mitotic count (MC). Statistical analysis was performed. Interobserver agreement for grade was moderate (κ = 0.497). Agreement was fair (κ = 0.375), moderate (κ = 0.491), and good (κ = 0.705) for grades 2, 3, and 1, respectively. Observer pair concordance ranged from fair to good (κ = 0.354–0.684) Perfect agreement was observed in 43 cases (30%). Interobserver agreement for the individual components was best for TF (κ = 0.503) and worst for MC (κ = 0.281). Seventeen of 86 (19.8%) discrepant cases would have resulted in changes in PS and discrepancies most frequently resulted in a PS change from IA to IB (n = 9). For two of these nine cases, Oncotype DX results would have led to a PS of 1A regardless of grade. Using VM, a multi-institutional cohort of pathologists showed moderate concordance for breast cancer grading, similar to studies using light microscopy. Agreement was the best at the extremes of grade and for evaluation of TF. Whether the higher variability noted for MC is a consequence of VM grading warrants further investigation. Discordance in grading infrequently leads to clinically meaningful changes in the prognostic stage. © 2020, The Author(s), under exclusive licence to United States & Canadian Academy of Pathology.
Keywords: adult; controlled study; human tissue; aged; major clinical study; microscopy; cancer recurrence; cancer staging; cancer grading; histology; breast carcinoma; mitosis rate; invasive carcinoma; digital imaging; bilateral cancer; virtual reality; cancer prognosis; human; female; priority journal; article
Journal Title: Modern Pathology
Volume: 34
Issue: 4
ISSN: 0893-3952
Publisher: Nature Research  
Date Published: 2021-04-01
Start Page: 701
End Page: 709
Language: English
DOI: 10.1038/s41379-020-00698-2
PUBMED: 33077923
PROVIDER: scopus
PMCID: PMC7987728
Notes: Article -- Export Date: 1 April 2021 -- Source: Scopus
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