The Bowel Cancer Screening Programme Expert Board: an analysis of activity during 2017–2020

Abstract

Aims:The inception of the National Health Service Bowel Cancer Screening Programme in England in 2006 highlighted the fact that the differential diagnosis between the presence of epithelial misplacement and adenocarcinoma occurring in colorectal adenomas is problematic. The pathology Expert Board (EB) was created to facilitate the review of difficult cases by a panel of three experienced gastrointestinal pathologists. This article describes a review of the work of the EB over a 4-year period (2017-2020). Methods and results: Four hundred and thirty polyps were referred to the EB from 193 pathologists and 76 hospitals during this time. The EB diagnosis was benign for 67%, malignant for 28%, and equivocal for 2% (with no consensus in the remainder). The most common diagnosis change made by the EB was from malignant to benign-made in 50% of polyps referred with an initially malignant diagnosis. The level of agreement between the individual EB members was 'good' (kappa score of 0.619) but that between the EB and the referring diagnosis was 'poor' (kappa score of 0.149). Data from one EB member indicated that the presence of lamina propria, features of torsion and cytological similarity between the superficial and deep glands were predictors of a benign diagnosis, whereas the presence of irregular neoplastic glands, a desmoplastic reaction and lymphovascular invasion were commonly observed features in polyps with a malignant diagnosis. Conclusion: Diagnostic agreement between EB members is better than that between the EB and referring pathologists. There was a consistent trend for the EB to change diagnoses from malignant to benign.

Expert opinion in bowel cancer screening pathology

“…7 Interobserver agreement was found to be better between panel members than between the panels and the referrers. 6,7 This is similar to previous studies and presumably reflects the greater levels of experience in the assessment of these polyps by panel members, who will be specialist gastrointestinal pathologists. 10 The English panel was set up with three members in order to maximize the chance of creating an opinion that is at least a consensus based on a 2:1 majority.…”

“…Bateman et al found that their panel changed a malignant to a benign diagnosis in 50% of polyps referred with the former diagnosis (to the nearest whole percent). 6 Smits et al found a 'discrepancy' rate between their panel and referring pathologists of 39% in adenomas and 53% of adenocarcinomas (to the nearest whole percent). Within the 'adenoma' group, most of the discrepancies were in the adenoma type and the grade of dysplasia.…”

“…7 In conclusion, the studies by Bateman et al and Smits et al illustrate the value of expert opinion in bowel cancer screening-derived histopathology and highlight the utility of pathology panels for achieving consensus in difficult cases. 6,7 Conflicts of interest None.…”

“…In this issue, Bateman et al and Smits et al assess inter-observer variability between expert pathology panels and referring pathologistsand between panel memberswithin bowel cancer screening programmes in England and the Netherlands respectively. 6,7 Both of these referral panels were created as a source of support for bowel cancer screening programme pathologists. Bateman et al describe their clinical experience in real time over a 4-year period in which almost all referrals to their panel (the 'Expert Board') were related to the differential diagnosis between epithelial misplacement and stage pT1 adenocarcinoma.…”

“…However, Bateman et al found that, in practice, many panel opinions were based on unanimous agreement. 6 Similarly, the Dutch panel comprised five members, three of whom reviewed each case. 7 There is great variability in the threshold for referring cases for expert opinion.…”