Adjunctive Treatment of Oral Tumors
Stephen Withrow United States
Although the vast majority of oral tumors will be treated with surgery, there are some well-defined (and not so well-defined) indications for adjuvant radiation and chemotherapy. Another alternative to traditional surgery is cryosurgery. Cryosurgery is only used for small lesions (< 2 cm diameter) with minimal bone invasion. The most common tumors treated are benign epulides. Malignant and potentially life threatening cancers are best treated by surgical resection so that adequate margins can be attained.
Radiation therapy is increasingly available in veterinary medicine. Its use in the management of cancer is increasing. It can be used palliatively (pain and symptom relief), curatively, alone, or in combination with surgery. Canine acanthomatous epulides and squamous cell carcinomas are considered radiation responsive. Radiation may be used alone or after incomplete surgical resection. Canine fibrosarcoma and most nondental tumors in cats (especially squamous cell carcinoma) are considered radiation resistant. Canine oral melanoma may respond better to course fraction radiation (6 Gy once or twice per week x 6 treatments) than to standard full course radiation. The rare cases of oral lymphoma or plasma cell tumors should be very radiation responsive. The role of radiation to treat involved draining lymph nodes remains undefined but is conceptually equivalent to or superior to surgery.
Most oral tumors (especially melanoma and fibrosarcoma) are considered chemoresistant. Rare articles suggest partial response of canine squamous cell carcinoma to cisplatin. Intralesional chemotherapy has been described but results are varied. The rare lymphoma, plasma cell, or transmissible venereal cell tumor should be responsive to conventional chemotherapeutics.
A wide variety of “other” adjuvant treatments has been described including immunotherapy, phototherapy, hyperthermia, gene therapy, etc. Although rare responses have been documented, these treatments do not replace conventional treatment with surgery.
Either esophagostomy or gastrostomy tubes should be considered in some patients undergoing course radiation or after extensive mandibulectomy, maxillectomy, or glossectomy.
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