The two most common kinds of skin cancer are basal cell carcinoma and squamous cell carcinoma. Basal cell carcinoma accounts for more than 90 percent of all skin cancers in the United States. It is a slow-growing cancer that seldom spreads to other parts of the body. Squamous cell carcinoma also rarely spreads, but it does so more often than basal cell carcinoma. However, it is important that skin cancers be found and treated early because they can invade and destroy nearby tissue.

Basal cell carcinoma and squamous cell carcinoma are sometimes called nonmelanoma skin cancer. Another type of cancer that occurs in the skin is melanoma, which begins in the melanocytes.

Most head and neck cancers begin in the squamous cells that line the structures found in the head and neck. Because of this, head and neck cancers are often referred to as squamous cell carcinomas. Some head and neck cancers begin in other types of cells. For example, cancers that begin in glandular cells are called adenocarcinomas.

Cancers of the head and neck are further identified by the area in which they begin:

Oral cavity—The oral cavity includes the lips, the front two-thirds of the tongue, the gums (gingiva), the lining inside the cheeks and lips (buccal mucosa), the bottom (floor) of the mouth under the tongue, the bony top of the mouth (hard palate), and the small area behind the wisdom teeth.

Salivary glands—The salivary glands are in several places: under the tongue, in front of the ears, and under the jawbone, as well as in other parts of the upper digestive tract.

Paranasal sinuses and nasal cavity—The paranasal sinuses are small hollow spaces in the bones of the head surrounding the nose. The nasal cavity is the hollow space inside the nose.

Pharynx—The pharynx is a hollow tube about 5 inches long that starts behind the nose and leads to the esophagus (the tube that goes to the stomach) and the trachea (the tube that goes to the lungs).