Impact on colorectal cancer pathology reporting practice of migration from TNM 5 to TNM 8

Maurice Loughrey, Olivia Kent, Michelle Moore, Caroline Coghlin, Paul Kelly, Gerard McVeigh, Helen Coleman

Research output: Contribution to journalArticle

Abstract

Introduction The introduction of TNM 8 into UK pathology practice in January 2018 considers tumour deposits in colorectal cancer staging for the first time. The impact of this new classification on pathology reporting practices has yet to be evaluated. Methods A clinical audit was conducted, comparing consecutive colorectal cancer resection specimens reported under TNM 5 classification guidelines in 2017 (n=177) and TNM 8 guidelines in 2018 (n=234). Tumour features (venous invasion, perineural invasion, lymph node metastatic disease, tumour deposits) and changes in reporting practices were evaluated amongst four specialist gastrointestinal pathologists working within a large pathology department. Results Adoption of TNM 8 practice led to approximate doubling in the use of ancillary stains (41.0% of TNM 8 v. 22.0% of TNM 5 cases, p<0.001) to help evaluate tumours. A narrowing of the range between pathologists was observed in reporting cases as having one or more form of regional, extramural, discontinuous tumour (TNM 5 range 50.0‐79.0%, TNM 8 range 57.8‐65.7%) with no change in the overall proportion of cases reported as such (62.7% v. 62.4%, p=0.95). However, significant inter‐observer variation in reporting rates for individual parameters remained. Conclusion TNM 8 colorectal cancer staging offers potentially greater reproducibility in pathology reporting of regional, extramural, discontinuous disease with similar proportions of patients reported as having one or more of these forms of tumour spread, compared with TNM 5. Further guidance in defining individual features is required to further reduce inter‐observer variation in pathology assessments and to help elucidate the clinical significance of each parameter.
Original languageEnglish
JournalHistopathology
Early online date13 Jun 2020
DOIs
Publication statusEarly online date - 13 Jun 2020

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