title: HYPOFRACTIONATED RADIOTHERAPY FOR MACROSCOPIC CANINE SOFT TISSUE SARCOMA: A RETROSPECTIVE STUDY OF 50 CASES TREATED WITH A 5 × 6 GY PROTOCOL WITH OR WITHOUT METRONOMIC CHEMOTHERAPY.
abstract: Wide surgical resection or a marginal/incomplete resection followed by full-course radiation therapy is the current standard of care for canine soft tissue sarcoma. The purpose of this retrospective, descriptive, bi-institutional study was to determine the effectiveness and toxicity of a hypofractionated 5 × 6 Gy protocol on macroscopic canine soft tissue sarcoma in terms of progression-free interval (PFI) and overall survival (OS), and to identify prognostic factors for patient outcome. Dogs with macroscopic soft tissue sarcoma irradiated with 5 × 6 Gy were eligible for the study. Progression-free interval and OS were compared with respect to different tumor and patient characteristics by the Kaplan-Meier method and multivariable Cox regression analysis. Fifty dogs with macroscopic disease were included. All dogs received the same radiation therapy protocol; part of the group (n = 20) received postradiation metronomic chemotherapy. Median PFI for all cases was 419 days (95% confidence interval (CI): 287-551) and median OS was 513 days (95% CI: 368-658). Dogs with tumors on the limbs had significantly longer PFI and OS, compared with head or trunk. Increasing tumor burden decreased OS. The addition of metronomic chemotherapy yielded a significantly longer OS (757 days (95% CI: 570-944) compared with dogs that did not receive systemic treatment (286 days (95% CI: 0-518), (P = 0.023)), but did not influence progression-free interval. Toxicity was low throughout all treatments. The 5 × 6 Gy radiation therapy protocol was well tolerated and provided long PFI and OS in dogs with macroscopic soft tissue sarcoma.
authors.affiliation: Centro Oncologico Veterinario, 40037, Sasso Marconi (BO), Italy.
authors.forename: Simona
authors.initials: S
authors.lastname: Cancedda
authors.affiliation: Centro Oncologico Veterinario, 40037, Sasso Marconi (BO), Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Marconato
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: Centro Oncologico Veterinario, 40037, Sasso Marconi (BO), Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Laganga
authors.affiliation: Division of Biostatistics, Epidemiology Biostatistics and Prevention Institute, Faculty of Medicine, University of Zurich, CH-8001, Zürich, Switzerland.
authors.forename: Malgorzata
authors.initials: M
authors.lastname: Roos
authors.affiliation: Centro Oncologico Veterinario, 40037, Sasso Marconi (BO), Italy.
authors.forename: Vito F
authors.initials: VF
authors.lastname: Leone
authors.affiliation: Centro Oncologico Veterinario, 40037, Sasso Marconi (BO), Italy.
authors.forename: Federica
authors.initials: F
authors.lastname: Rossi
authors.affiliation: Division of Radiation Oncology, Vetsuisse Faculty, University of Zurich, CH-8057, Zurich, Switzerland.
authors.forename: Carla Rohrer
authors.initials: CR
authors.lastname: Bley
mesh_terms: D059250:Administration, Metronomic / Q000662:veterinary; D000818:Animals; D000970:Antineoplastic Agents / Q000008:administration & dosage / Q000494:pharmacology; D018450:Disease Progression; D004283:Dog Diseases / Q000188:drug therapy* / Q000532:radiotherapy*; D004285:Dogs; D005260:Female; D008297:Male; D012189:Retrospective Studies; D012509:Sarcoma / Q000188:drug therapy / Q000532:radiotherapy / Q000662:veterinary*
chemical_list: D000970:Antineoplastic Agents
keywords: dog; metronomic chemotherapy; radiotherapy; soft tissue sarcoma