title: Prognostic value of histologic grading for feline mammary carcinoma: a retrospective survival analysis.
abstract: Feline mammary carcinoma is highly malignant and generally associated with a poor prognosis, although studies suggest the range of survival times in affected cats is broad. Histologic grading of these tumors is achieved using the Elston and Ellis system, originally developed for human breast cancer. In cats, however, classification using this method has variable prognostic value. Therefore, objectives of this study were (1) to evaluate the Elston and Ellis grading system for feline mammary carcinoma in a predominantly spayed population and (2) to determine whether modification of this system or development of a novel system improved the prognostic value of histologic grading. Survey data and histologic features for 108 carcinomas from 97 cats were analyzed with respect to overall survival. Elston and Ellis grading failed to correlate significantly with overall survival. Using multivariable analysis, lymphovascular invasion, nuclear form, and mitotic count each demonstrated independent prognostic significance (P = .008, <.001, and .004, respectively). Modifications of the Elston and Ellis system and a novel grading system were proposed based on these results; all showed significant correlation with overall survival (P < .001). Median survival times were 27, 29, or 31 months for grade I; 14, 12, or 14 months for grade II; and 13, 5, or 8 months for grade III carcinomas using the mitotic-modified Elston and Ellis, the revised Elston and Ellis, or the novel grading system, respectively. Based on this retrospective study, adoption of the species-specific systems as proposed here may improve the prognostic value of histologic grading for feline mammary carcinoma.
authors: Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK, Canada Indicates equal contribution swm570@mail.usask.ca.
authors: S W
authors: SW
authors: Mills
authors: Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK, Canada Indicates equal contribution.
authors: K M
authors: KM
authors: Musil
authors: Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada.
authors: J L
authors: JL
authors: Davies
authors: Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK, Canada.
authors: S
authors: S
authors: Hendrick
authors: College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO, USA.
authors: C
authors: C
authors: Duncan
authors: Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK, Canada.
authors: M L
authors: ML
authors: Jackson
authors: Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK, Canada.
authors: B
authors: B
authors: Kidney
authors: Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK, Canada.
authors: H
authors: H
authors: Philibert
authors: Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK, Canada.
authors: B K
authors: BK
authors: Wobeser
authors: Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK, Canada.
authors: E
authors: E
authors: Simko
mesh_terms: D000818:Animals; D002277:Carcinoma / Q000175:diagnosis / Q000401:mortality / Q000473:pathology / Q000662:veterinary*; D002371:Cat Diseases / Q000175:diagnosis* / Q000401:mortality / Q000473:pathology; D002415:Cats; D005260:Female; D015674:Mammary Neoplasms, Animal / Q000175:diagnosis* / Q000401:mortality / Q000473:pathology; D008940:Mitotic Index; D060787:Neoplasm Grading / Q000662:veterinary; D011379:Prognosis; D012189:Retrospective Studies; D013045:Species Specificity; D016019:Survival Analysis
keywords: Elston and Ellis; feline mammary carcinoma; grading; prognosis; retrospective postoperative survival; tumor histology