Proton Irradiation of Feline Nasal Planum Squamous Cell Carcinomas Using an Accelerated Protocol

Abstract

Fifteen cats were treated for squamous cell carcinoma of the nasal planum using proton beam radiation. The protocol used was accelerated with eight equal fractions given on four consecutive days, with a minimum of six hours between fractions. Total dose of radiation delivered was escalated with nine cats receiving 40.4 CGE (60Co Gy equivalent), and three cats each receiving 42.4 and 44.8 CGE. Complete response to the protocol was 60% (9/15), partial response was 33% (5 of 15), and no response was seen in 6.6% (1 of 15). Tumor control rate at one year was 64% and no cat had tumor recurrence after one year. Median survival was 946 days (+/- 516 days). Side effects were minimal with no severe reactions noted in the early or late period. This protocol offers an effective treatment for squamous cell carcinoma of the feline nasal planum with minimal side effects and may be adaptable to conventional radiation sources particularly when the field size is very small.

Ki67 Reactivity in Nasal and Periocular Squamous Cell Carcinomas in Cats Treated with Electron Beam Radiation Therapy

“…Hypofractionation means that larger doses per fraction are given to achieve a shorter overall treatment time, but the risk of delayed toxicity is increased. 10 In a previous study, 8 an accelerated, hypofractionated proton radiation therapy regimen was shown to be efficatious and well tolerated for the treatment of feline squamous cell carcinomas. DFI of cats in this study was 440 days with a 1-year DFI of 64%.…”

“…In contrast to surgery, radiation therapy was found to be a cosmetically appealing and effective option. 4,[6][7][8] Squamous cell carcinomas are thought to be rapidly dividing tumors. A potential tumor doubling time of approximately 5 days was determined by using flow cytometry and bromodeoxyuridine (BrdU) staining.…”

A utilização da radioterapia no tratamento do carcinoma de células escamosas cutâneo felino avançado

“…As lesões muito avançadas, em estágio T 4 , corresponderam a 87% (6/7) do total de lesões tratadas neste trabalho. Na literatura é descrito que lesões avançadas têm menor sucesso ao tratamento radioterápico do que lesões em fases iniciais (Theon et al, 1995;Fidel et al, 2001). Théon et al (1995) analisaram o prognóstico de 90 lesões de CE felino tratadas através de radioterapia, e chegaram à conclusão de que neoplasias estadiadas como T 1 tiveram uma melhor resposta do que as neoplasias estadiadas como T 4 .…”

“…A taxa estimada de remissão completa foi calculada apenas para estágios T 1 (56%), porém a taxa de resposta geral não foi mencionada. Fidel et al (2001) usaram um protocolo acelerado com feixe de prótons com energia de 72 MeV e com dose total de 40.4 CGE a 44,8 CGE. Com esse protocolo, obtiveram a taxa de 60% de remissão completa duradoura e 33% de remissão parcial nos 15 gatos portadores de CCE tratados.…”

Terapêutica no carcinoma de células escamosas cutâneo em gatos

“…Radiação com feixe de prótons foi aplicada, por FIDEL et al (2001), em 15 gatos com carcinoma de células escamosas no plano nasal. A média de sobrevivência foi de 946 dias.…”