Squamous cell carcinoma (epidermoid carcinoma)
DESCRIPTION: In excess of 90% of all oral cancers are of the squamous cell type. As stated in other sections in this monograph, early carcinoma may clinically appear as leukoplakia or erythroplasia. It may also appear as a mixture of erythroplasia and leukoplakia. Another common clinical appearance is an area of chronic ulceration.
Squamous carcinoma is about three times as common in men as in women. Risk of acquiring the disease increases with each passing decade but is seldom seen in those under forty. According to the American Cancer Society, there are about 21,000 new cases of oral cancer in the United States each year, an incidence rate of approximately 8 cases per 100,000 persons. Although no area of oral mucosa is immune, certain areas are more vulnerable. Soft palate, lateral and ventral tongue mucosa, and floor of the mouth are especially prone to develop squamous carcinoma. The tongue and floor of the mouth are the most common areas.
ETIOLOGY: The cause is unknown. Smoking and alcohol are risk factors, and the human papilloma virus is suspect. Time will show that mutations in genes that control the cell cycle, protooncogenes and tumor suppressor genes, are at the heart of many forms of cancer including oral cancer.
TREATMENT: Usual treatment consists of surgical excision and possible irradiation. Chemotherapy is adjunctive at this time.
PROGNOSIS: The overall five year survival rate is about 50%. Early diagnosis increases the chance of survival.
DIFFERENTIAL DIAGNOSIS: All ulcerations present for more than 2-3 weeks in which there is no apparent cause should be biopsied to rule out carcinoma, especially in adults whose lesions are in high risk areas.
