Types

The oral cavity and oropharynx contain several types of tissue, and each tissue contains several types of cells. Different cancers develop from each kind of cell. The differences are important, because they influence the patient's treatment options and prognosis.

Leukoplakia, Erythroplakia, and Dysplasia

Leukoplakia and erythroplakia refer to abnormal areas in the mouth or throat. Leukoplakia is a white area. Erythroplakia is a slightly raised, red area that bleeds easily if scraped. Determining the seriousness of these conditions requires a biopsy.

These white or red areas may be a cancer, or they may be a precancerous condition called dysplasia. They could also be some relatively harmless condition. There are mild, moderate, and severe forms of dysplasia. Knowing the degree of dysplasia may indicate how likely it is to develop into cancer. Often dysplasia will go away if the factor that causes it is eliminated. Smoking and/or chewing tobacco frequently cause these conditions. Applying drugs related to vitamin A (retinoids) may help eliminate dysplasia or prevent other spots from forming.

Most of the time, leukoplakia does not develop into cancer. Only about 5 percent of leukoplakias are either cancerous or precancerous (and likely to progress to cancer within 10 years if not properly treated). Erythroplakia is usually more serious. As many as half are diagnosed as cancer at the time of initial biopsy.

Malignant Oral Cavity and Oropharyngeal Tumors

More than 90 percent of cancers of the oral cavity and oropharynx are squamous cell carcinomas. Squamous cell cancer begins as a collection of abnormal squamous cells. The earliest form is referred to as carcinoma in situ. Invasive squamous cell cancer means that the cancer cells have spread beyond this layer into deeper layers of the oral cavity or oropharynx.

Verrucous carcinoma is a type of squamous cell carcinoma that makes up less than 5 percent of all oral cavity tumors. It is a low-grade cancer that rarely metastasizes but can spread deeply into surrounding tissue.

Minor salivary gland cancers can develop in the minor salivary glands found throughout the mucosal lining of the oral cavity and oropharynx. There are several types of minor salivary gland cancers: adenoid cystic carcinoma, mucoepidermoid carcinoma, and polymorphous low-grade adenocarcinoma.

The tonsils and base of tongue contain lymphatic tissue that also can develop into a cancer.