oral fibrosarcoma in cats
Background
The second most common oral tumor in cats is fibrosarcoma. There is no obvious breed or gender predilection. Fibrosarcoma is most common in old cats that average 10 years of age.
Clinical Parameters
Feline fibrosarcoma is found mostly in the oral gingivae but has no obvious site predilection. The lesion may be ulcerated, causing halitosis and drooling, and is difficult to distinguish clinically from squamous cell carcinoma.
Clinical Work-up
Staging procedures should be performed as discussed for squamous cell carcinoma. Fibrosarcomas cause tissue destruction and occasionally invade bone or muscle. On histopathologic examination these fibrosarcomas often have a high mitotic index; however, metastatic potential appears low.
Therapeutic Approach
Two cats were treated with hemimandibulec- tomy or premaxillectomy and were free of disease 11.5 months and 24 months after surgery, respectively. In another two cats treated with hemimandibulectomy, one cat had recurrence in 2 months, and one cat failed to eat and was euthanized. A gastrostomy tube should be placed in all cats undergoing oral surgery.
Vincristine (0.5 mg/m2 intravenously per week) caused complete regression of an oral fibrosarcoma in one cat when treated for 30 weeks. Other chemotherapy for this tumor has not been described, although doxorubicin reportedly causes regression of fibrosarcoma at other sites in cats. Oral piroxicam (0.14 mg/lb every other day) may be of benefit in these cats.
Because of the encouraging results of radiation therapy in cats with other soft tissue sarcomas (including fibrosarcoma), this modality in combination with surgery may offer the best chance of tumor control in cats, as it does in dogs. Doxorubicin or carboplatin have been employed with variable results.