Non-Odontogenic Oral Tumors

General Comments:
The oral cavity is the fourth most common site of malignant neoplasia in dogs and cats. 10% of all feline and 6% of all canine tumors are in the oral cavity. Cancer of the mouth is 2.6 times more frequent in dogs than cats and male dogs are 2.4% more likely to have oral malignancy than females. 90% of all feline oral tumors are malignant. With the malignant melanomas, high grade sarcomas, and tonsillar squamous cell carcinomas, distant metastasis may be a complication by the time the tumor is recognized. Most other oral tumors do not involve metastasis.

Except for oral papillomatosis (caused by papovavirus-DNA), the cause of canine and feline oral neoplasia is undetermined.

For information on Odontogenic Tumors (OTs), please refer to odontogenic tumors (epulides).

Common Presenting Complaints:
Owners may notice: drooling or bleeding from the mouth, oral malodor, difficulty chewing, dysphagia, observation of an intra- or extra oral mass or facial asymmetry. It is important to understand that many of our oral tumors are not recognized in the early stages. By the time many of our pet patients demonstrate symptoms, the disease process may be relatively advanced.

Diagnostic Work-up: 
Typical work-ups will include blood work, radiology and biopsies.

Blood work usually involves a general blood profile (CBC, blood chemistries, electrolytes). Other specialized tests such as clotting profiles and blood type determination and cross-matching are important prior to procedures that may involve significant hemorrhage.

Radiology may entail thoracic radiographs to rule out existing metastatic disease to the chest.  Intra-oral (dental) radiographs are indicated for almost all oral tumors. Specific areas can be isolated with intra-oral radiography and because dental X-Ray film is non-screened film, fine details are much more apparent (when compared to standard radiographic film). Additional diagnostics may include skull radiographs and in many cases, advanced imaging such as a CT or MRI scan will also be needed to determine the 3 dimensional extent of the disease process.

Taking a proper biopsy specimen is indicated for all oral masses and for any suspicious lesions. Deep biopsy sections are necessary because superficial samples may reveal only inflammation, infection or gingival hyperplasia. A definitive histopathogic diagnosis (biopsy) is the foundation for all oncological decision-making. A definitive biopsy diagnosis is an absolute must before determining a treatment plan and performing the treatment.

Regional lymph node assessment may be necessary depending upon the histopathologic diagnosis. Biopsy and possible removal of regional lymph nodes may be important aspects of tumor staging and treatment.

Patients with previously untreated tumors typically survive longer after surgery than those with recurrent tumors. In general, the smaller the tumor size and more rostral the location, the more favorable the prognosis for all tumor types. In addition, for squamous cell carcinomas, young age and maxillary location carry a better prognosis.

Early diagnosis and careful oncologic treatment planning may result in sastifactory long-term survival for cats and dogs with oral malignancy.

Treatment Options: 
Options depend on the tumor type (diagnosis), size, location and extent of the disease. Because most oral tumors are locally aggressive and uncommonly metastasize; wide surgical excision is the treatment of choice for achieving local tumor control; however radiation therapy is a frequent adjunctive treatment for some tumor types. Systemic chemotherapy may benefit patients with moderate to high-grade oral tumors, metastatic disease, or non-resectable primary tumors.

For many cases, if a tumor is amenable, surgical excision is usually the most cost effective therapy and the most likely to be associated with longer-term survival or be curative. Because wide surgical excisions are often necessary, a partial mandibulectomy or maxillectomy may be required. Functional and cosmetic results with surgery are good, and most pet owners are pleased with the post-operative results.

Radiation therapy may be used alone or in combination with surgery. The development of surgery-radiation combination treatment modalities has dramatically improved survival rates for patients with oral tumors. Radiation is often used if a tumor is inoperable or post-op if tumor cells extend beyond the surgical margins. Occasionally, owners do not wish to pursue aggressive oral surgery and elect radiation therapy for palliative purposes only. “Palliative” tumor treatment uses radiation with the goal to improve the quality of remaining life with as few side-effects as possible. Extension of life is not an intention of this type of therapy.