Continued research along these avenues is indicated, as cats are excellent natural models for human head and neck squamous cell carcinoma because of similarities in tumor behavior, response to therapy, possible etiologies, and p53 expression.²⁹ Using cats as a natural model for this disease may benefit both cats and people by providing veterinarians with new ways to treat this aggressive cancer and by providing information that may be applied to the human counterpart of the disease.

Supportive treatment

Supportive care is critical during treatment of cats with oral squamous cell carcinoma. These cats are often in pain and may be in a poor nutritional state because of their tumors. The cautious use of analgesics should be considered in patients suffering from large and bulky tumors; tumors that have ulcerated; or painful metastatic lesions. Although many analgesics are considered extralabel for use in cats, medications such as nonsteroidal anti-inflammatory drugs and opioids may be beneficial in supportive treatment in advanced cases. Adequate nutrition is also critical in supportive care, and the placement of an esophageal feeding tube or gastrostomy tube may be necessary. The goal of these supportive therapies is to maintain the patient in a comfortable and nutritionally healthy state while allowing the chosen therapy time to have effect against the tumor. In the authors' experiences, supportive care alone in these cases extends survival time only minimally.

Local control of feline oral squamous cell carcinoma is poor with currently investigated therapies, including surgery, hyperthermia, chemotherapy, and radiation therapy.² The overall poor survival times in cats with oral squamous cell carcinoma may reflect the tumor's location, as sublingual and maxillary tumors are rarely resectable, and also the fact that this tumor is often diagnosed late in the course of the disease. Early diagnosis followed by aggressive local treatment and appropriate supportive care is the best way to improve survival times.

Feline oral squamous cell carcinomas grow rapidly, ultimately causing pain and affecting a patient's ability to eat and drink. Ninety percent of cats die within 12 months of initial diagnosis²; almost all are euthanized because of local disease. Untreated, cats with large masses often are euthanized within weeks of diagnosis because of progressive pain and anorexia. Cats with bulky tumors that cannot be widely excised live a median of two to three months with therapies including surgery, radiation, or chemotherapy.^{5,19,20,21,25} The best prognosis is for cats with mandibular squamous cell carcinoma in which mandibulectomy with or without radiation therapy can be performed; these cats have a median survival time of five to 14 months, with 43% of cats living two years in one study.^4,6,16-18

SUMMARY

Oral squamous cell carcinoma is a common malignancy in cats that responds poorly to treatment. The ideal approach for management is early diagnosis by using oral examination, radiographic evaluation including advanced imaging techniques, biopsy, and radical surgical excision. Recurrence despite aggressive surgical resection is common, thus multimodality therapy appears to be indicated. Cats that have been treated with mandibulectomy and curative-intent radiation postoperatively have had the longest survival times. Mandibulectomy has a high associated morbidity, but the overall quality of life of the patients was thought to be good by most owners. Current research focuses on delineating the biologic pathways involved in malignant transformation and progression with the hope of improving therapeutic options for cats.

Jennifer J. Marretta, DVM
Laura D. Garrett, DVM, DACVIM (oncology)
Sandra Manfra Marretta, DVM, DACVS, DAVDC
Department of Veterinary Clinical Medicine
College of Veterinary Medicine
University of Illinois
Urbana, IL 61802