What are cancers of the head and neck?
Cancers that are known collectively as head and neck cancers usually begin in the squamous cells that line the moist, mucosal surfaces inside the head and neck (for example, inside the mouth, the nose, and the throat). These squamous cell cancers are often referred to as squamous cell carcinomas of the head and neck. Head and neck cancers can also begin in the salivary glands, but salivary gland cancers are relatively uncommon. Salivary glands contain many different types of cells that can become cancerous, so there are many different types of salivary gland cancer.
Cancers of the head and neck are further categorized by the area of the head or neck in which they begin. These areas are described below and labeled in the image of head and neck cancer regions.
Oral cavity: Includes the lips, the front two-thirds of the tongue, the gums, the lining inside the cheeks and lips, the floor (bottom) of the mouth under the tongue, the hard palate (bony top of the mouth), and the small area of the gum behind the wisdom teeth.
Pharynx: The pharynx (throat) is a hollow tube about 5 inches long that starts behind the nose and leads to the esophagus. It has three parts: the nasopharynx (the upper part of the pharynx, behind the nose); the oropharynx (the middle part of the pharynx, including the soft palate [the back of the mouth], the base of the tongue, and the tonsils); the hypopharynx (the lower part of the pharynx).
Larynx: The larynx, also called the voicebox, is a short passageway formed by cartilage just below the pharynx in the neck. The larynx contains the vocal cords. It also has a small piece of tissue, called the epiglottis, which moves to cover the larynx to prevent food from entering the air passages.
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.
Salivary glands: The major salivary glands are in the floor of the mouth and near the jawbone. The salivary glands produce saliva.
Head and neck cancer regions. Illustrates location of paranasal sinuses, nasal cavity, oral cavity, tongue, salivary glands, larynx, and pharynx (including the nasopharynx, oropharynx, and hypopharynx).
Cancers of the brain, the eye, the esophagus, and the thyroid gland, as well as those of the scalp, skin, muscles, and bones of the head and neck, are not usually classified as head and neck cancers.
Sometimes, cancerous squamous cells can be found in the lymph nodes of the upper neck when there is no evidence of cancer in other parts of the head and neck (1). When this happens, the cancer is called metastatic squamous neck cancer with unknown (occult) primary. More information about this cancer type can be found in Metastatic Squamous Neck Cancer with Occult Primary (PDQ®).
What causes cancers of the head and neck?
Alcohol and tobacco use (including smokeless tobacco, sometimes called “chewing tobacco” or “snuff”) are the two most important risk factors for head and neck cancers, especially cancers of the oral cavity, oropharynx, hypopharynx, and larynx (2–5). At least 75 percent of head and neck cancers are caused by tobacco and alcohol use (6). People who use both tobacco and alcohol are at greater risk of developing these cancers than people who use either tobacco or alcohol alone (6–8). Tobacco and alcohol use are not risk factors for salivary gland cancers.
Infection with cancer-causing types of human papillomavirus (HPV), especially HPV-16, is a risk factor for some types of head and neck cancers, particularly oropharyngeal cancers that involve the tonsils or the base of the tongue (9–11). In the United States, the incidence of oropharyngeal cancers caused by HPV infection is increasing, while the incidence of oropharyngeal cancers related to other causes is falling (9). More information is available in the HPV and Cancer fact sheet.
Other risk factors for cancers of the head and neck include the following:
Paan (betel quid). Immigrants from Southeast Asia who use paan (betel quid) in the mouth should be aware that this habit has been strongly associated with an increased risk of oral cancer (12, 13).
Maté. Consumption of maté, a tea-like beverage habitually consumed by South Americans, has been associated with an increased risk of cancers of the mouth, throat, esophagus, and larynx (13, 14).
Preserved or salted foods. Consumption of certain preserved or salted foods during childhood is a risk factor for nasopharyngeal cancer (15, 16).
Oral health. Poor oral hygiene and missing teeth may be weak risk factors for cancers of the oral cavity (17, 18). Use of mouthwash that has a high alcohol content is a possible, but not proven, risk factor for cancers of the oral cavity (17, 18).
Occupational exposure. Occupational exposure to wood dust is a risk factor for nasopharyngeal cancer (15, 16). Certain industrial exposures, including exposures to asbestos and synthetic fibers, have been associated with cancer of the larynx, but the increase in risk remains controversial (19). People working in certain jobs in the construction, metal, textile, ceramic, logging, and food industries may have an increased risk of cancer of the larynx (20). Industrial exposure to wood or nickel dust or formaldehyde is a risk factor for cancers of the paranasal sinuses and nasal cavity (21–23).
Radiation exposure. Radiation to the head and neck, for noncancerous conditions or cancer, is a risk factor for cancer of the salivary glands (17, 24, 25).
Epstein-Barr virus infection. Infection with the Epstein-Barr virus is a risk factor for nasopharyngeal cancer (26) and cancer of the salivary glands (27, 28).
Ancestry. Asian ancestry, particularly Chinese ancestry, is a risk factor for nasopharyngeal cancer (15, 16).