The term head and neck cancers refers to a group of cancers found in the head and neck region. This includes tumors found in the oral cavity (mouth), the oropharynx (which includes the back one-third of the tongue, the back of the throat and the tonsils); the nasopharynx (which includes the area behind the nose); the hypopharynx (lower part of the throat), and the larynx (voice box, located in front of the neck, in the region of the Adam's apple). The most frequently occurring cancers of the head and neck area are oral cancers and laryngeal cancers. Almost half of all the head and neck cancers occur in the oral cavity, and a third of the cancers are found in the larynx. By definition, the term "head and neck cancers" usually excludes tumors that occur in the brain.

Although the exact cause...