Response of Feline Oral Squamous Cell Carcinoma to Palliative Radiation Therapy

Abstract

Seven cats with advanced oral squamous cell carcinoma were treated with palliative radiotherapy. Megavoltage radiation in 8 Gray (Gy) fractions was delivered on days 0, 7, and 21 for a total dose of 24 Gy. Treatment field included the mandible, oropharynx, retropharyngeal lymph nodes, and tonsils. Adjuvant treatment with chemotherapy was variable. Age ranged from 13 to 18 years old with a median age of 15 years. Three of the seven cats (43%) did not complete treatment. Six cats were euthanized due to tumor growth and/or radiation side effects with a median survival time of 60 days (range = 42 to 97 days, mean = 63 +/- 8.4 days). Radiotherapy complications or progression of disease occurred in 6 of 7 (85.7 %) cats and included adverse clinical signs, such as mucositis, serosanguinous oral discharge, pain, and dysphagia. These data suggest that coarse fractionation radiotherapy did not result in palliation in cats with inoperable oral squamous cell carcinoma.

Palliative care in small animal oncology

“…External beam radiation is a versatile therapy and can be used in the palliative setting for both tumour control and analgesia (Brearley and others 1999, Ramirez and others 1999, Bregazzi and others 2001, Moore 2002, Farrelly and McEntee 2003, Mayer and Grier 2006, Plavec and others 2006, Coomer and others 2009, Poirier and others 2013, Fujiwara-Igarashi and others 2014, Kung and others 2014) (Figs 4, 5). At the time of writing, there are six veterinary radiation facilities with linear accelerators in the UK (Box 3).…”

A Naturally Occurring Feline Model of Head and Neck Squamous Cell Carcinoma

“…Radiation therapy as a single-agent therapy results in overall response rates of 54%–70%, median progression-free intervals of 1.8–3.5 m, and median survival times of 2–5.8 m [22, 32, 33]. Similar to human studies, in cats chemotherapy as a single agent for primary tumor control is considered ineffective [21].…”

“…Overall, median survival times are generally between 2 and 4 months, with a one-year survival of only 10% [27, 29, 33, 36]. While disappointing, these numbers underscore the potential to institute investigational therapies in cats with rapid timelines for study completion.…”

Radiation therapy

“…15-6). 8,9 Feline injection site sarcoma In veterinary medicine the treatment of soft tissue sarcoma by a combination of surgical resection (Chapter 22) followed by local adjuvant radiation has become accepted as an effective method for management of those tumors arising at sites where wide surgical resection is not feasible, e.g., distal limbs. 15-7).…”