Federica Rossi1,2, Laura Marconato1, Silvia Sabattini3, Simona Cancedda1, Paola Laganga1, Vito F Leone1, Carla Rohrer Bley4. 1. 1 Veterinary Oncology Centre, Sasso Marconi, Italy. 2. 2 Orologio Veterinary Centre, Sasso Marconi, Italy. 3. 3 Department of Veterinary Medical Sciences, University of Bologna, Ozzano Emilia, Italy. 4. 4 Division of Radiation Oncology, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland.
Abstract
OBJECTIVES: The aim of this retrospective, bi-institutional study was to evaluate the progression-free interval in a cohort of cats with postoperative microscopic injection-site sarcoma (ISS) treated with two different radiotherapy protocols. METHODS: Included in the study were cats with ISSs undergoing macroscopic surgical removal and subsequent electron beam radiotherapy treatment with either a finely fractionated protocol (48 or 52.8 Gy over 4 weeks delivered in 12 or 16 fractions) or a coarsely fractionated protocol (36 Gy over 3 weeks administered in six fractions). Medical records were reviewed and follow-up information was collected. The Kaplan-Meier method and log-rank test were used to compare the progression-free interval (PFI) between the two protocols and to test the influence of many clinical variables. RESULTS: Fifty-nine cats were included; 38 underwent a finely fractionated protocol and 21 a coarsely fractionated protocol. PFI was not significantly different between the two groups. Overall PFI was 2000 days (2000 vs 540 days; P = 0.449). When only first-occurrence cases were included, median PFI was significantly longer in the finely fractionated group compared with the coarsely fractionated group (1430 vs 540 days; P = 0.007). In cats that underwent multiple surgeries PFI was not different between protocols (233 vs 395 days; P = 0.353). CONCLUSIONS AND RELEVANCE: Cats with first-occurrence ISSs appear to benefit from postoperative finely fractionated radiotherapy. The same benefit was not evident in cats that underwent multiple surgeries and we think a coarsely fractionated protocol would be indicated in these cases.
OBJECTIVES: The aim of this retrospective, bi-institutional study was to evaluate the progression-free interval in a cohort of cats with postoperative microscopic injection-site sarcoma (ISS) treated with two different radiotherapy protocols. METHODS: Included in the study were cats with ISSs undergoing macroscopic surgical removal and subsequent electron beam radiotherapy treatment with either a finely fractionated protocol (48 or 52.8 Gy over 4 weeks delivered in 12 or 16 fractions) or a coarsely fractionated protocol (36 Gy over 3 weeks administered in six fractions). Medical records were reviewed and follow-up information was collected. The Kaplan-Meier method and log-rank test were used to compare the progression-free interval (PFI) between the two protocols and to test the influence of many clinical variables. RESULTS: Fifty-nine cats were included; 38 underwent a finely fractionated protocol and 21 a coarsely fractionated protocol. PFI was not significantly different between the two groups. Overall PFI was 2000 days (2000 vs 540 days; P = 0.449). When only first-occurrence cases were included, median PFI was significantly longer in the finely fractionated group compared with the coarsely fractionated group (1430 vs 540 days; P = 0.007). In cats that underwent multiple surgeries PFI was not different between protocols (233 vs 395 days; P = 0.353). CONCLUSIONS AND RELEVANCE: Cats with first-occurrence ISSs appear to benefit from postoperative finely fractionated radiotherapy. The same benefit was not evident in cats that underwent multiple surgeries and we think a coarsely fractionated protocol would be indicated in these cases.
Authors: Jacqueline V J Cavalcanti; Kimberly A Selting; Mai T Ngo; Christine K Tran Hoang; David J Schaeffer; Timothy M Fan; Brendan A C Harley; Heidi Phillips Journal: Am J Vet Res Date: 2022-05-14 Impact factor: 1.055