Toxicity and outcome in cats with oral squamous cell carcinoma after accelerated hypofractionated radiotherapy and concurrent systemic treatment

Abstract

Recently, a multimodal approach to oral squamous cell carcinoma (SCC) in cats, combining medical treatment and accelerated radiation therapy, showed a substantial outcome improvement in a small pilot study. Herein we retrospectively review 51 cats with unresectable, histologically confirmed oral SCC and a complete initial staging work‐up: cats in group A (n = 24) received medical anti‐angiogenic treatment consisting of bleomycin, piroxicam and thalidomide, cats in group B (n = 27) received the anti‐angiogenic treatment and concurrent accelerated hypofractionated radiation therapy with 48Gy delivered in 10 fractions. Overall median progression‐free interval (PFI) was poor with 70 days (95% CI: 48;93). In the irradiated cats (group B), however, PFI was significantly longer with 179 days (95% CI: 58;301) days, vs 30 days (95% CI: 23;38) in medically only treated cats (P < .001). Overall median overall survival (OS) was 89 days (95% CI: 55;124), again significantly longer in the irradiated cats (group B) with 136 (95% CI: 40;233) vs 38 days (95% CI: 23;54) (P < .001). In 8 of the 27 (29.6%) cats in group B, however, severe toxicity (grade 3) occurred. Neither onset nor severity of toxicity could be associated with any of the tested variables, including anatomic site, tumour size, clinical stage and duration of neoadjuvant medical treatment. Given the potential severe acute effects and the impact on quality of life after chemo‐radiotherapy, owners must be clearly informed about the risks of treatment. With the overall poor outcome and high occurrence of acute toxicity, we cannot recommend the use of this accelerated radiation protocol combined with anti‐angiogenic therapy for oral SCC in cats.

Analysis of DNA methylation and TP53 mutational status for differentiating feline oral squamous cell carcinoma from non‐neoplastic mucosa: A preliminary study

“…This largely limits the efficacy of treatments, including surgery, radiation therapy and chemotherapy, and increases treatment‐related morbidity. The prognosis is poor for the majority of cats, and even with a multi‐modal therapeutic approach the median survival time rarely exceeds 12 months 4,5 …”

“…The prognosis is poor for the majority of cats, and even with a multi-modal therapeutic approach the median survival time rarely exceeds 12 months. 4,5 Recently, a significantly higher prevalence of TP53 gene mutations was observed in FOSCC compared with normal oral mucosa and inflammatory lesions; this provides another similarity between feline and human disease, and suggests the diagnostic utility of p53 for the detection of oral cancer in cats. 6 Over the last two decades, epigenetic alterations have been receiving increasing attention as promoters of tumour initiation and progression, in addition to and even more frequently than structural inactivation of genes by mutations and deletions.…”

Early radiation‐induced oral pain signaling responses are reduced with pentoxifylline treatment

“…Definitive‐intent treatment of head and neck cancers (HNC) is associated with a high risk for debilitating normal tissue complications. The incidence of acute oral mucositis and pharyngitis in humans undergoing chemoradiotherapy for HNC is nearly 100%; similar risk has been reported for companion animals undergoing certain intensive HNC treatment protocols 15–17 . When severe, (chemo)radiation‐induced oral mucositis can necessitate breaks in treatment; a well‐described consequence of such treatment delays is reduced probability of local tumor control 18–21 .…”

Outcomes of cats treated with maxillectomy: 60 cases. A Veterinary Society of Surgical Oncology retrospective study

“…One of these cats, a cat with a benign amyloid‐producing odontogenic tumour treated with a palliative radiation protocol, subsequently developed local tumour recurrence. The combination of mandibulectomy and radiation therapy resulted in the best reported survival times for cats with mandibular SCC with a MST of 14 months 23 compared with 217 days or less for cats treated with mandibulectomy alone or other modalities; 9,11‐16,24‐27 however, only seven cats were included in this study and six of these cats were euthanized because of local tumour recurrence. The role of radiation therapy in the treatment of cats with incompletely excised oral tumours requires further investigation.…”