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Cancer is a group of related diseases that begin in cells, the body’s basic unit. Normally, cells grow and divide to form new cells in an orderly way and eventually die. If they do not die, but instead continue to divide and create new cells that are not needed, they can form a growth or "tumor." Tumors can be either "benign" or "malignant." Benign tumors do not invade nearby tissue or spread to other parts of the body. Malignant tumors invade normal structures near the tumor and spread to other organs in the body. These are the characteristics of what is called "cancer." Cancers of the Head and Neck Most head and neck cancers begin in the cells that line the surfaces of the mouth, nose, and throat. Normal mucosal cells look like scales ("squamous") under the microscope, so head and neck cancers are often referred to as "squamous cell carcinomas." Because some cancers begin in other types of cells like those in glands, the tumors are called "adenocarcinomas." Cancers of the head and neck are also classified by the area in which they begin: Oral cavity: (including the lips, the front two-thirds of the tongue, the gums, the lining inside the cheeks and lips, the bottom of the mouth under the tongue, the hard palate and the small area behind the wisdom teeth) Salivary glands: (these glands produce saliva to keep mucosal surfaces in the mouth and throat moist; there are many salivary glands, but the major ones are in the floor of the mouth, and near the jaw in front of the ear) Paranasal sinuses and nasal cavity: (the paranasal sinuses are small hollows in the bones of the head around the nose; the nasal cavity is the hollow space inside the nose) Pharynx: (the pharynx is a tube that starts behind the nose and leads to the esophagus (the"swallowing" tube) and the trachea (the main "breathing" tube). Three parts of the pharynx:
Larynx: (the larynx, or "voicebox," is a short passageway of cartilage that leads to the windpipe and contains the vocal cords; also has a small piece of tissue called the epiglottis, which covers the larynx to prevent food from entering) Lymph nodes: (sometimes squamous cancer cells are
found in the lymph nodes of the neck when there is no sign of cancer
elsewhere; this is called metastatic squamous neck cancer with unknown
primary) Causes of Head and Neck Cancer Tobacco (including "chewing tobacco" or "snuff") and alcohol use are the most important risk factors, particularly those of the mouth, throat and voicebox (larynx). More than 80 percent of head and neck cancers are linked to tobacco use. People who use both tobacco and alcohol are at greatest risk. Other risk factors:
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