Page 1316 - Clinical Small Animal Internal Medicine

1254 Section 11 Oncologic Disease

Signalment Table 137.1 WHO staging system for oral tumors
VetBooks.ir In contrast to other malignant oral tumors, OMM tends Stage Tumor size and metastasis status

to occur in smaller breed dogs as well as some large
breeds, with an average age at presentation of 12 years. I <2 cm diameter tumor
Cocker spaniel, miniature poodle, Anatolian sheepdog, II 2 to <4 cm diameter tumor
Gordon setter, chow chow, and golden retriever are over-
represented. The average age of a dog presenting with an III >/= 4 cm diameter tumor and/or lymph node metastasis
oral SCC is 8–10 years, while the average age for a cat is IV Distant metastasis
10–12 years. Oral FSAs tend to occur in large‐breed
dogs, particularly the golden and Labrador retriever. The superior bone detail. Both provide more information on
average age at presentation is 7–9 years and there appears the local extent of the tumor than regional radiographs.
to be a male predisposition. Dogs presenting with Information obtained from CT or MRI is critical in the
fibromatous and ossifying epulides are typically 8–9 planning of definitive surgery and radiation.
years, and a male predisposition has been reported. Regional lymph nodes should be carefully palpated for
Shetland and old English sheepdogs are predisposed to enlargement or asymmetry. Caution should be exercised,
acanthomatous ameloblastomas. The average age at however, when making clinical judgments based on pal-
presentation is 7–10 years, and a sex predisposition is pation alone, as lymph node size is not an accurate pre-
not reported.
dictor of metastasis. Lymph node aspirates should be
performed in all animals with oral cancers, regardless of
their size or mobility. Three‐view thoracic radiographs
History and Clinical Signs
are recommended to evaluate animals for evidence of
Cats and dogs with rostral oral cancer commonly pre- pulmonary metastatic disease. Thoracic CT scans should
sent for a mass noted by the owner. Cancer in the caudal be considered for animals with highly metastatic tumor
oral cavity is rarely noted by owners and the animals types such as OMM, since CT scans are more sensitive
often present at an advanced stage of disease, resulting in for detecting pulmonary metastatic lesions. Based on
fewer options for treatment. Clinical signs may include these diagnostic steps, oral tumors are then staged
hypersalivation, exophthalmos or facial swelling, according to the World Health Organization’s staging
epistaxis, weight loss, halitosis, bloody oral discharge, scheme (WHO) (Table 137.1).
dysphagia or pain on opening the mouth. Occasionally,
cervical lymphadenopathy (especially in squamous cell Therapy
carcinoma of the tonsil) is also found. Complete oral
examinations should always be performed during health Surgery
exams as early intervention may allow for more treat- Surgical resection is the gold standard for oral tumors
ment options and an improved prognosis. and is the most commonly used modality for achieving
local control. The surgical approach depends on tumor
type and location. The majority of tumors involving the
Diagnosis
maxilla, mandible, and hard palate will have underlying
Due to the wide range of cancer behavior and recom- bone involvement so surgical resection should include
mended treatment options for oral cancers, diagnostic bony margins to increase the likelihood of complete
evaluation is critical. A biopsy is required for the defini- excision. Minimum margins of at least 2 cm, and prefer-
tive diagnosis, and this will assist the clinician in deter- ably 3 cm, are recommended for malignant tumors such
mining the biologic behavior and prognosis of the tumor. as SCC, OMM, and FSA in the dog.
Impression smear or fine needle aspirate cytology prepa-
rations of the tumor are generally not rewarding, as Radiation Therapy
many oral tumors are associated with a high degree of Radiation therapy can be used with palliative or curative
necrosis and inflammation. Most animals will require a intent, or as an adjunct to surgery for incompletely
short general anesthesia for careful mass evaluation, resected tumors or tumors with aggressive local behav-
regional radiographs, and biopsy. An incisional biopsy of ior. Radiation therapy can be considered a primary treat-
the mass is recommended. ment of canine oral SCC, OMM, and some benign tumors
Advanced imaging is recommended for oral tumors such as epulides. These tumors are radiation responsive,
arising from the maxilla, palate, and caudal mandible. even when treated in the setting of gross disease.
Computed tomography (CT) scans are generally pre- Radiation protocols used for the treatment of these
ferred to magnetic resonance imaging (MRI) because of tumors have involved daily or alternate‐day treatments