title: Immunohistochemical Labelling for Cyclo-oxygenase-2: Does the Positive Control Guarantee Standardized Results?
abstract: Since the identification of cyclo-oxygenase-2 as a potentially important therapeutic target in veterinary oncology, numerous studies on its expression have been conducted. Unfortunately, results have been heterogeneous and conclusions are difficult to draw. We tested the ability of a defined positive control to guarantee reproducibility of results among different laboratories. Valid positive controls were defined by positivity of the renal macula densa without background labelling. Fifteen colorectal tumours and 15 oral squamous cell carcinomas were labelled immunohistochemically by six European laboratories. Slides were evaluated in blinded fashion for percentage of positive cells and labelling intensity by three pathologists, and results were analyzed statistically for reproducibility and inter-reader variability. Macula densa positivity was an insufficiently sensitive control to guarantee reproducible results for percentage of positive cells and labelling intensity. Inter-reader variability was proven statistically, making the case for image analysis or other automated quantitative evaluation techniques.
authors.affiliation: Equipe Recherche UPSP ICE 2011-03-101: Oncology, Vetagro-sup, Campus Vétérinaire, 1 Avenue Bourgelat, Marcy l'etoile, France. Electronic address: sara.belluco@vetagro-sup.fr.
authors.forename: S
authors.initials: S
authors.lastname: Belluco
authors.affiliation: Department of Comparative Biomedicine and Food Science, Faculty of Veterinary Medicine, AGRIPOLIS, Viale dell'Università 16, Legnaro, Italy.
authors.forename: P
authors.initials: P
authors.lastname: Carnier
authors.affiliation: Department of Comparative Biomedicine and Food Science, Faculty of Veterinary Medicine, AGRIPOLIS, Viale dell'Università 16, Legnaro, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Castagnaro
authors.affiliation: Faculty of Veterinary Medicine, University of Ghent, Salisburylaan 133, Merelbeke, Belgium.
authors.forename: K
authors.initials: K
authors.lastname: Chiers
authors.affiliation: Department of Animal Pathology, School of Veterinary Medicine, University of Pisa, Viale delle Piagge 2, Pisa, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Millanta
authors.affiliation: Veterinary School, Complutense University Madrid, Madrid, Spain.
authors.forename: L
authors.initials: L
authors.lastname: Peña
authors.affiliation: University of Trás-os-Montes and Alto Douro, Quinta de Prados, Vila Real, Portugal.
authors.forename: I
authors.initials: I
authors.lastname: Pires
authors.affiliation: University of Trás-os-Montes and Alto Douro, Quinta de Prados, Vila Real, Portugal.
authors.forename: F
authors.initials: F
authors.lastname: Queiroga
authors.affiliation: Merial, 254 rue Marcel Mérieux, Lyon, France.
authors.forename: S
authors.initials: S
authors.lastname: Riffard
authors.affiliation: Bridge Pathology Ltd., Courtyard House, 26A Oakfield Road, Bristol, UK.
authors.forename: T
authors.initials: T
authors.lastname: Scase
authors.affiliation: North Downs Specialist Referrals, Friesian Building 3&4, The Brewer Street Dairy Business Park, Brewer Street, Bletchingley, Surrey, UK.
authors.forename: G
authors.initials: G
authors.lastname: Polton
mesh_terms: D000818:Animals; D002294:Carcinoma, Squamous Cell / Q000201:enzymology / Q000662:veterinary*; D015179:Colorectal Neoplasms / Q000201:enzymology / Q000662:veterinary*; D051546:Cyclooxygenase 2 / Q000032:analysis*; D007150:Immunohistochemistry / Q000592:standards*; D009062:Mouth Neoplasms / Q000201:enzymology / Q000662:veterinary*; D015588:Observer Variation; D015203:Reproducibility of Results; D014730:Veterinary Medicine / Q000592:standards*
chemical_list: D051546:Cyclooxygenase 2
keywords: cyclo-oxygenase-2; immunohistochemistry; inter-reader variability; reproducibility