The way a particular head and neck cancer behaves depends on the site in which it arises (the primary site). For example, cancers that begin in the vocal cords behave very differently than those that arise in the back of the tongue, which is only an inch or less from the vocal cords.

The most common type of cancer in the head and neck is squamous cell carcinoma, which arises from the cells that line the inside of the nose, mouth and throat. Squamous cell cancer is often associated with a history of smoking, or exposure to the human papilloma virus (HPV). Other less common types of head and neck cancers include salivary gland tumors, lymphomas and sarcomas. Methods of prevention include avoidance of exposure to tobacco products and vaccination of children and young adults against HPV.

Cancers spread in three main ways. The first is direct extension from the primary site to adjacent areas. The second is spread through the lymphatic channels to lymph nodes. The third is spread through the blood vessels to distant sites in the body. In head and neck cancer, a spread to the lymph nodes in the neck is relatively common.

The lymph nodes most commonly involved are located along major blood vessels underneath the sternocleidomastoid muscle on each side of the neck, particularly the internal jugular vein node at the angle of the jaw. The risk of spread to other parts of the body through the bloodstream is closely related to whether the cancer has spread to the lymph nodes in the neck, how many nodes are involved, and their location in the neck. The risk is higher if cancer is in lymph nodes in the lower part of the neck rather than only in those located in the upper neck.

The diagnosis of cancer of the head and neck is often made by a dentist, oral surgeon or physician after a patient notices symptoms such as a sore in the mouth that does not heal, or a lump in the neck. Even without symptoms, the diagnosis may be made during a routine examination.