Treatment of Oral Cancer
World Small Animal Veterinary Association World Congress Proceedings, 2009
Michèle Venturini, AFA, Médica Veterinária (USP), Cirurgiã Dentista (USP)
Mestre pelo Departamento de Cirurgia da FMVZ-USP; Sócia-Proprietária do ODONTOVET, Centro Odontológico Veterinário, Butantã, São Paulo, SP, Brasil

With the evolution of veterinary medicine, dogs and cats are living more and reaching old age. Therefore, maturities diseases are more frequents. Oral tumors represent approximately 5% of all neoformation in dogs and cats. Many tumors types, both benign and malignant, occur in the oral tissues. Malignant tumors most common in this species are malignant melanoma, squamous cell carcinoma and fibrosarcoma. Most of benign tumors are epulis (Bjorling, 2003). Epulis are classified in osseous, fibromatous and acanthomatous locally aggressive. According to Harvey and Emily (1993), those four types of tumors represent 80% of all oral neoplasia in dogs and only the squamous cell carcinoma represent 70% of all neoplasias in cats.

Animals with oral neoplasms are brought in for examination because of the owner notice an oral mass or because of excessive salivation, bleeding from the mouth, difficulty in mastication, dysphagia, halitosis, oral pain, facial swelling, facial asymmetry, mobile or displaced teeth, lethargy, respiratory distress or weight loss may be seen (Harvey & Emily, 1993; Wiggs & Lobprice, 1997). The advanced age of most animals with oral neoplasms make essential a thorough evaluation of systemic health before any procedure. The most critical procedure in the evaluation of a patient with oral neoplasia is obtaining and examining a biopsy specimen. The biopsy must avoid areas of superficial necrosis and must sample the deeper, viable tissue. Excisional biopsy, a wedge biopsy or a needle punch technique can be used. To determine the presence and extend of bone and soft tissues invasion, usually present in malignant tumors, skull or jaw radiographs and computed tomography should be taken in all animals with gingival or palatine tumors or when any tumor is fixed to underlying bone. Thoracic radiographs should be obtained for all animals with suspected oral malignancy. All those procedures allow the surgeon to establish the diagnosis, formulate a treatment regiment and give the owner an accurate prognosis.

The management of oral neoplasms depends on accurate diagnosis and staging of the disease and knowledge of the biologic behaviour of individual tumors types and the advantages and limitations of available treatments modalities. There is no protocol available that is adequate for all tumors, therapy must e individualized. Surgery resection should be the first choice of treatment when possible. Conservative resection of oral masses is indicated occasionally. Viral papillomatosis lesions, most frequent seen in young animals, are easily resected by transecting the stalk of the lesion. Benign gingival lesions, such as gingival hyperplasia or fibrous/osseous epulis lesions are likely to regrow after resection at a tissue level that does not the bone from which they arise. Other neoplastic masses should not be treated by conservative surgery. Radical surgery as partial or hemimandibulectomy, premaxillectomy or partial maxillectomy may provide a cure in some cases and is tolerated surprisingly by dogs and cats. Small malignant lesions should be treated radically. The choice and aggressiveness of treatment will depend on the extension of tumor involvement (local or with metastasis), type of tumor and physical conditions of the patient. Radical surgery is still the treatment most indicated. If not possible or not accepted by the owner, it is possible to use radiation therapy for tumors radio sensible as squamous cell carcinoma. Chemotherapy and immunotherapy also can be used with poor results. There use is indicated in conjunction with aggressive surgery to prevent metastasis or when margins are not free of malignant cells. Lately, electro-immunotherapy has been used in oral tumors with some good results.

In most cases, first purpose of a surgical treatment is patient cures that can be obtain with adequate removal of the tumor, free margins and absence of metastasis. If the lesion is so that those items can not be reached, palliative surgery should be considered. The purpose of this treatment is not to obtain the cure of patient but improve life quality and permit the use of another modality of treatment as radiotherapy.

Owner orientations previous to the surgery are extremely important. The nature of the procedure, complications and specially expectation should be discussed with the owner. Show the owner pictures of patients that have been submitted to the same radical surgery can be helpful. The owner must be aware about the prognosis of malignant disease.


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Speaker Information
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Michèle A. F. A. Venturini, médica veterinaria (USP), cirurgia dentista (USP)
Sao Paulo, SP, Brazil

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