title: Anal cancer subtype reproducibility study.
abstract: For histological subtyping of anal squamous carcinomas the WHO advocates a six-way subdivision, but it has been suspected that the six types cannot be reliably discriminated in practice. We conducted a blinded study involving slides from 103 consecutive cases, each slide being examined by three experts (from Denmark, Australia and UK) on two occasions at least 8 months apart. Agreement on subtypes was low: 72% between rounds within pathologist, 61% between pathologists. Even for the commonest, and most stably diagnosed, type, viz. large-cell keratinising squamous carcinoma, the intra- and interpathologist frequencies of confirmation were only 81% and 71%, respectively. The pathologist marked the picture as typical and his subtype diagnosis as certain 41% of times: even then confirmation frequencies were only 88% and 74%, respectively. Calculations, including kappa analyses, suggest that 26% of the typing variation was noise. The WHO scheme must be even more unreliable in everyday practice. We finally mention a recently demonstrated link between human papilloma virus (HPV) and certain types of anal cancer, which may well provide an additional argument for revising existing subtyping schemes.
authors.affiliation: Department of Pathology, Odense University Hospital, Denmark. claus.fenger@ouh.dk
authors.forename: C
authors.initials: C
authors.lastname: Fenger
authors.forename: M
authors.initials: M
authors.lastname: Frisch
authors.forename: J J
authors.initials: JJ
authors.lastname: Jass
authors.forename: G T
authors.initials: GT
authors.lastname: Williams
authors.forename: J
authors.initials: J
authors.lastname: Hilden
mesh_terms: D001005:Anus Neoplasms / Q000145:classification* / Q000175:diagnosis / Q000473:pathology*; D002294:Carcinoma, Squamous Cell / Q000145:classification* / Q000175:diagnosis / Q000473:pathology*; D006801:Humans; D012016:Reference Values