Diagnostic criteria for gastrointestinal carcinomas in Japan and Western countries: Proposal for a new classification system of gastrointestinal epithelial neoplasia

Background: Large differences have been found between Western and Japanese pathologists in their diagnosis of adenoma/dysplasia and early carcinoma fo r gastric, colorectal and oesophageal epithelial neoplastic lesions. Common worldwide terminology based on clinical usefulness, that is, on neoplastic severity and depth of invasion, is needed. Methods: Thirty-one pathologists from 12 countries reviewed 35 gastric, 20 colorectal and 21 oesophageal biopsy and resection specimens. The extent of diagnostic agreement between those with Western and Japanese viewpoints wa s assessed by kappa statistics. Results: Suspected or definite carcinoma was diagnosed in 17-66% of gastric , in 5-40% of colorectal, and in 10-67% of oesophageal slides by pathologis ts with a Western viewpoint, but in 77-94% of gastric, in 45-75% of colorec tal and in 81-100% of oesophageal slides by pathologists with a Japanese vi ewpoint (from Japan, Germany, Austria and UK). Overall, there was poor agre ement between the conventional Western and Japanese diagnoses (kappa values lower than 0.3 for gastric, colorectal and oesophageal lesions). There was much better agreement among the pathologists (kappa values higher than 0.5 for gastric and colorectal lesions) when the original assessments of the s lides were regrouped into the five categories of the following classificati on of GI epithelial neoplasia we hereby propose: C1, negative for neoplasia ; C2, indefinite for neoplasia; C3, mucosal low-grade neoplasia (low-grade adenoma/dysplasia); C4, mucosal high-grade neoplasia (high-grade adenoma/dy splasia plus mucosal carcinoma); C5, submucosal invasion of neoplasia. Conclusions: The intercountry differences in the diagnoses of adenoma/dyspl asia and early carcinoma can, in large part, be resolved by adopting termin ology based on neoplastic severity and depth of invasion. Problems with def ining intramucosal invasion are thus avoided. Moreover, grouping high-grade adenoma/dysplasia and mucosal carcinoma together in one category is clinic ally useful, as patients with small mucosal neoplastic lesions can be cured by endoscopic local resection. (C) 2000 Blackwell Science Asia Pty Ltd.