title: Retrospective clinical study on outcome in cats with nasal planum squamous cell carcinoma treated with an accelerated radiation protocol.
abstract: BACKGROUND
  Cutaneous squamous cell carcinoma of the nasal planum in cats is a common indication for antitumor treatment such as external beam radiation therapy. Curative-intent radiation therapy has been described as a valuable treatment option, resulting in long and stable tumor control in these patients. The aim of the current study was to evaluate outcome and toxicity, as well as possible prognostic factors using an accelerated hypofractionated radiation therapy protocol. Cats with squamous cell carcinoma of the nasal planum treated with an accelerated radiation protocol (10 × 4.8 Gy, over one week) were retrospectively evaluated. Tumor- and treatment-associated variables were evaluated in respect to local control and survival.
  
  
  RESULTS
  Forty-four cats met the inclusion criteria for this study. All cats showed complete response to therapy. Median disease-free interval (DFI) for all cases was 916 days (95% CI: 456-1377). One- and two-year DFIs were 71% (95% CI: 56-86%) and 60% (95% CI: 43-77%). Of the tested variables, only tumor volume showed a tendency to influence DFI, with larger tumors having a 5.4 times greater risk of recurrence than the smaller ones (HR 1.33 (95% CI: 0.99-1.79), p = 0.054). Median overall survival (OS) was 902 days (95% CI: 862-942). One- and 2-year OSs were 79.3% (95% CI: 67.3-91.3) and 58.4% (95% CI: 42.8-74). Of the tested variables, again, only tumor volume influenced OS with larger tumors having a 6.3 times greater risk of dying than the smaller ones (HR 1.36 (95% CI: 1.07-1.73), p = 0.010). The acute and late toxicity profile was low and hence clinically acceptable.
  
  
  CONCLUSIONS
  Curative-intent radiation therapy with an accelerated fractionation schedule can be considered a safe, cosmetically superior treatment option for cutaneous squamous cell carcinomas of the nasal planum in cats, resulting in long and stable tumor control.
authors.affiliation: Division of Radiation Oncology, Vetsuisse-Faculty, University of Zurich, CH-8057, Zurich, Switzerland.
authors.forename: Evgeniya
authors.initials: E
authors.lastname: Gasymova
authors.affiliation: Division of Radiation Oncology, Vetsuisse-Faculty, University of Zurich, CH-8057, Zurich, Switzerland.
authors.forename: Valeria
authors.initials: V
authors.lastname: Meier
authors.affiliation: Institute of Veterinary Pathology, Vetsuisse Faculty, University of Zurich, CH-8057, Zurich, Switzerland.
authors.forename: Franco
authors.initials: F
authors.lastname: Guscetti
authors.affiliation: Centro Oncologico Veterinario, 40037, Sasso Marconi (BO), Italy.
authors.forename: Simona
authors.initials: S
authors.lastname: Cancedda
authors.affiliation: Department of Biostatistics, Epidemiology Biostatistics and Prevention Institute, Faculty of Medicine, University of Zurich, CH-8001, Zurich, Switzerland.
authors.forename: Malgorzata
authors.initials: M
authors.lastname: Roos
authors.affiliation: Division of Radiation Oncology, Vetsuisse-Faculty, University of Zurich, CH-8057, Zurich, Switzerland. crohrer@vetclinics.uzh.ch.
authors.forename: Carla
authors.identifier: http://orcid.org/0000-0002-5733-2722
authors.initials: C
authors.lastname: Rohrer Bley
mesh_terms: D000818:Animals; D002294:Carcinoma, Squamous Cell / Q000532:radiotherapy / Q000662:veterinary*; D002371:Cat Diseases / Q000532:radiotherapy*; D002415:Cats; D018572:Disease-Free Survival; D005260:Female; D008297:Male; D009669:Nose Neoplasms / Q000532:radiotherapy / Q000662:veterinary*; D012189:Retrospective Studies; D012878:Skin Neoplasms / Q000532:radiotherapy / Q000662:veterinary*; D016896:Treatment Outcome
keywords: Accelerated protocol; Cat; Nasal planum; Radiation therapy; Squamous cell carcinoma