A New Etiology of Head and Neck Cancer: Human Papillomavirus
The traditional risk factors for head and neck cancer include alcohol and tobacco. As the rates of tobacco use have decreased there has been a corresponding decrease in the rates of many head and neck cancers. The oropharynx is one site of the head and neck that unfortunately has demonstrated a digression from this trend. The two most prominent structures of the oropharynx are the palatine tonsils and the base of tongue. Malignancies in these areas have been associated with infection by the human papilloma virus (HPV). Tumors of the oropharynx that are HPV-positive are increasing at a rate of 5% per year. Interestingly, the increased incidence of HPV-positive oropharyngeal cancers is occurring almost exclusively in men. The rates of HPV-positive oropharyngeal cancers in women are changing at a much lower rate.
What is HPV?
HPV is a DNA virus that is responsible for a variety of benign and malignant conditions. There are more than 150 different sub-types of the virus that can be divided into low risk and high risk. High-risk types are associated with cervical cancer, anogenital cancer and more recently with squamous cell carcinoma of the oropharynx, while low-risk types cause common warts, genital warts and both sinonasal and upper aerodigestive tract papillomas. The common strains identified in otolaryngology include low-risk types 6 and 11 (associated with papillomas), and high-risk types 16 and 18 (associated with squamous cell carcinoma).
How are HPV-positive tumors different?
There are notable differences between cancers that are attributed to alcohol and tobacco and those attributed to HPV.
The patterns of treatment for oropharyngeal cancer have undergone several shifts over the last two decades. Surgery followed by radiation was the common approach for several decades. These surgeries were done through large neck incisions and often resulted in significant morbidity. Clinical trials exploring non-surgical treatments utilizing a combination of chemotherapy and radiation demonstrated improved oncologic outcomes with less morbidity, and these treatments became the standard of care.
Technological advances have led to renewed interest in surgery through less invasive approaches. Transoral robotic surgery (TORS) and transoral laser microsurgery (TLM) are both techniques that allow for removal of tumors by working through the mouth and avoiding an external approach through neck incisions. Advantages of endoscopic over open approaches include improved swallowing function, decreased complications, shorter hospital stay and avoidance of a tracheotomy.
The overall outcomes among patients with HPV-positive cancers are superior to those with HPV-negative cancers. This is true for both radiation and surgery. The high cure rates for HPV-positive cancers have started to shift the focus toward minimization of long-term treatment related morbidities.
There are two commercially available vaccines that target the main HPV strains associated with oropharyngeal carcinoma (HPV-16 and HPV-18). They have not been studied for use in the prevention of head and neck cancer, but have demonstrated protection against cervical and anogenital disease caused by the same pathogenic virus. Gardasil® is approved for boys and girls aged 9-26. There are also new clinical trials open exploring the role of transoral surgery and less toxic courses of radiation in the treatment of this novel disease.
For More Information
The providers at the Ear, Nose and Throat Clinic at UW Health offer a wide range of care and treatment for patients with ear, nose, throat, head and neck disorders. If you would like to refer a patient to our staff, our list of clinics in Madison and around the region will help you find a provider who can discuss individual cases with you.
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