title: International study group on rectal cancer regression grading: interobserver variability with commonly used regression grading systems.
abstract: The aim of this study was to ascertain the level of concordance among gastrointestinal pathologists for regression grading in rectal cancers treated with neoadjuvant chemoradiation. Seventeen gastrointestinal pathologists participated using the Mandard, Dworak, and modified rectal cancer regression grading systems to grade 10 representative slides that were selected from 10 cases of rectal cancer treated with long-course neoadjuvant chemoradiation. The slides were scanned with a whole-slide scanner generating dynamic digitized images. The results showed very little concordance across the 3 grading systems, with κ values of 0.28, 0.35, and 0.38 for the Mandard, Dworak, and modified rectal cancer regression grading systems, respectively. In only 1 of 10 study cases was there unanimous grading concordance using the modified rectal cancer regression grading system. It was felt that these systems lacked precision and clarity for reproducible, accurate regression grading. The study concluded that there was a need for a simple, reproducible regression grading system with clear criteria, a cumulative or composite score taking into account all sections of the tumor bed that is sampled rather than the worst section (highest grade), and there should be a uniform method of sampling of these specimens.
authors.affiliation: Department of Cellular Pathology, John Radcliffe Hospital and University of Oxford, OX3 9DU Oxford, UK. runjan.chetty@ndcls.ox.ac.uk
authors.forename: Runjan
authors.initials: R
authors.lastname: Chetty
authors.forename: Pelvender
authors.initials: P
authors.lastname: Gill
authors.forename: Dhirendra
authors.initials: D
authors.lastname: Govender
authors.forename: Adrian
authors.initials: A
authors.lastname: Bateman
authors.forename: Hee Jin
authors.initials: HJ
authors.lastname: Chang
authors.forename: Vikram
authors.initials: V
authors.lastname: Deshpande
authors.forename: David
authors.initials: D
authors.lastname: Driman
authors.forename: Marisa
authors.initials: M
authors.lastname: Gomez
authors.forename: Godman
authors.initials: G
authors.lastname: Greywoode
authors.forename: Eleanor
authors.initials: E
authors.lastname: Jaynes
authors.forename: C Soon
authors.initials: CS
authors.lastname: Lee
authors.forename: Michael
authors.initials: M
authors.lastname: Locketz
authors.forename: Corwyn
authors.initials: C
authors.lastname: Rowsell
authors.forename: Anne
authors.initials: A
authors.lastname: Rullier
authors.forename: Stefano
authors.initials: S
authors.lastname: Serra
authors.forename: Neil
authors.initials: N
authors.lastname: Shepherd
authors.forename: Eva
authors.initials: E
authors.lastname: Szentgyorgyi
authors.forename: Rajkumar
authors.initials: R
authors.lastname: Vajpeyi
authors.forename: Lai Mun
authors.initials: LM
authors.lastname: Wang
authors.forename: Andrew
authors.initials: A
authors.lastname: Bateman
mesh_terms: D000230:Adenocarcinoma / Q000145:classification / Q000473:pathology* / Q000628:therapy; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D007391:International Cooperation; D020360:Neoadjuvant Therapy; D060787:Neoplasm Grading; D015588:Observer Variation; D012004:Rectal Neoplasms / Q000145:classification / Q000473:pathology* / Q000628:therapy; D015203:Reproducibility of Results