Alcohol and tobacco use (including secondhand smoke and 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, hypopharynx, and voice box (3–7). People who use both tobacco and alcohol are at greater risk of developing these cancers than people who use either tobacco or alcohol alone (8, 9). Most head and neck squamous cell carcinomas of the mouth and voice box are caused by tobacco and alcohol use (8).

Infection with cancer-causing types of human papillomavirus (HPV), especially HPV type 16, is a risk factor for oropharyngeal cancers that involve the tonsils or the base of the tongue (10–12). 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 (10). About three-quarters of all oropharyngeal cancers are caused by chronic HPV infection (13, 14). Although HPV can be detected in other head and neck cancers, it appears to be the cause of cancer formation only in the oropharynx. The reasons for this are poorly understood. 

Other known risk factors for specific cancers of the head and neck include the following:

Paan (betel quid). The use of paan (betel quid) in the mouth, a common custom in Southeast Asia, is strongly associated with an increased risk of mouth cancers (15, 16). 

Occupational exposure. Occupational exposure to wood dust is a risk factor for nasopharyngeal cancer (17, 18). Certain industrial exposures, including exposures to asbestos and synthetic fibers, have been associated with cancer of the voice box, 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 voice box (20). Industrial exposure to wood dust, 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 (24–26).

Epstein-Barr virus infection. Infection with the Epstein-Barr virus is a risk factor for nasopharyngeal cancer (27) and cancer of the salivary glands (28, 29).

Ancestry. Asian ancestry, particularly Chinese ancestry, is a risk factor for nasopharyngeal cancer (17, 18).

Underlying genetic disorders. Some genetic disorders, such as Fanconi anemia, can increase the risk of developing precancerous lesions and cancers early in life (30).