The origin of head and neck cancer (HNC) has been linked to smoking and alcohol consumption, and more recently to infection by human papillomavirus family viruses (HPV). But an area that was obscure and where recent research is being unveiled is the actual cell of origin of HNC.

Ask any cancer survivor what his or her greatest fear is, and chances are he or she’ll reply: “The cancer coming back.” Recurrence rates from different cancers can vary widely, from 5 to 95 percent depending on how far the original tumor had spread, its particular molecular characteristics and other clinical factors. But what makes cancer come back?

A possible answer may get to the root of the cancer problem: cancer stem cells (CSCs).

CSCs can be thought of as generals in a war. There aren’t very many of them, they are located at the rear, and organize the battles and send in the troops to invade. They build the armies. Many scientists believe that CSCs originate and keep tumors growing, invading and spreading into new places. They also may make up less than 0.1 percent, or one in 1,000 cells, of a solid tumor’s bulk. They are not related to embryonic stem cells, other than their name who indicates that they are at the root of an event; in the case of embryonic stem cells it means that they give rise to an embryo, in the case of CSC it implies that they give rise to cancer.

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The incidence of head and neck cancer (HNC) has been gradually increasing over the last 3 decades. Although certain subsets of HNC (such as larynx cancer) have decreased in incidence in parallel with the reduction in smoking, rates of oral cavity tumors (including tongue and tonsil) have risen among young (<45 years old) men and women. In addition to the classic risk factors of tobacco and alcohol use (that used to be responsible for the majority of HNC) recent data have linked infection with a virus to cases of HNC especially from the oral cavity and related sites. The virus strains responsible belong to the human papillomavirus family (HPV). HPV is the main cause for cervix cancers in women, and the HPV subtypes associated with HNC are rather similar with those causing cervical cancer. Subtype HPV16 accounts for the majority of HPV-positive cases (> 65% of oral tumors, >80% of oropharynx cancers, and 70% of laryngeal cases), with HPV18 having a far second place (around 5-8% of HPV-positive cases). Epidemiological data seem to suggest that sexual transmission is important but other transmission routes are under investigation.

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