Getting Your Head Around the Human Papillomavirus

You may have heard about HPV’s role in cervical cancer, but what about head and neck cancer?

By Kari Bohlke, ScD

The human papillomavirus (HPV) has been in the news a great deal lately, but how much do you really know? Use this quiz to test your knowledge about this group of viruses.

  1. How many types of HPV are there?
  1. A.2
  2. B.4
  3. C.13
  4. D.more than 100
  1. What health conditions are linked with HPV infection?
  1. A.warts
  2. B.cervical cancer
  3. C.some head and neck cancers
  4. D.all of the above and more

The correct answers are D (more than 100) and D (all of the above and more). Some types of HPV cause warts, and other types of HPV have been linked with cancer. Much of the research on HPV and cancer has focused on HPV’s role in cancers of the cervix, vulva, and vagina, but HPV also contributes to cancers of the penis, anus, and oropharynx (the part of the throat that includes the tonsils, the base of the tongue, and the soft palate).[1]

The HPV infections that cause genital cancers are transmitted sexually. Infection is extremely common and generally occurs soon after an individual becomes sexually active. Many infections clear up on their own, but others persist and increase the risk of cancer.

Sexual transmission may also play an important role in HPV-related oropharyngeal cancers. In this case it is oral HPV infection that increases the risk of cancer. It’s still not completely clear how oral HPV infection occurs, but evidence suggests that oral sex and open-mouthed kissing may play a role.[2] The good news is that the same vaccines that reduce the risk of HPV-related genital cancer may also substantially reduce the risk of HPV-related oropharyngeal cancer.

HPV-related Head and Neck Cancer

Head and neck cancers originate in the tissues in or around the nose, mouth, and throat. Smoking and alcohol use have long been known to increase the risk of head and neck cancer, but more recently it’s become apparent that some cases of head and neck cancer—particularly oropharyngeal cancer—are linked with HPV infection.

It’s still uncertain how many cases of oropharyngeal cancer are due to HPV infection, but researchers have estimated that more than 7,000 cases of HPV-related oropharyngeal and oral cavity cancer occur each year in the United States.[3] In addition, an analysis of studies from around the world reported that 36 percent of oropharyngeal cancers contained HPV. By far the most common type of HPV detected was HPV type 16.[4]

In a study published in the New England Journal of Medicine, individuals with oral HPV 16 infections were more than 14 times more likely to have oropharyngeal cancer than uninfected individuals.[5] A greater number of sexual partners—particularly oral-sex partners—was also linked with an increased risk of oropharyngeal cancer.

Trends in the incidence of head and neck cancer provide additional support for a link between HPV and oropharyngeal cancer. Overall the incidence of head and neck cancers has decreased as smoking rates have declined. Incidence of oropharyngeal cancer has not declined, however, and appears to be increasing in young adults.[6]

An interesting observation about HPV-related oropharyngeal cancers is that they appear to have a better prognosis than oropharyngeal cancers due to smoking or other causes. A study of patients with Stage III or IV oropharyngeal cancer was presented at the 2009 Annual Meeting of the American Society of Clinical Oncology. Two-year overall survival was 88 percent among patients with HPV-positive cancers but only 66 percent among patients with HPV-negative cancers. Information about HPV status may eventually influence head and neck cancer treatment decisions.[7]

Prevention

As more evidence regarding HPV-related oropharyngeal cancer has emerged, attention has turned to prevention. Though there is limited information about how oral HPV infection occurs, oral sex and open-mouthed kissing may both play a role. Information about a probable link with oral sex is important for adolescents as well as adults in order to encourage safer sexual practices. Reports suggest that oral sex is a common practice among adolescents, who believe it to be safe.[8]

HPV vaccines may offer an additional means of prevention. Though direct evidence of a benefit against oropharyngeal cancer is not yet available, it is possible that vaccination will reduce risk. HPV 16 appears to account for a large majority of HPV-related oropharyngeal cancer, and both of the currently available HPV vaccines protect against this type of HPV.

The take-home message? The reach of HPV extends well beyond cervical cancer, affecting both men and women. Fortunately, as our understanding of HPV-related conditions has expanded, so has our understanding of how to prevent infection. Currently available HPV vaccines do not prevent infection with all types of HPV, but they are likely to substantially reduce the burden of HPV-related disease.

HPV Vaccines

The two HPV vaccines that are currently approved in the United States are Gardasil® (Quadrivalent Human Papillomavirus [types 6, 11, 16, 18] Recombinant Vaccine) and Cervarix® (Bivalent Human Papillomavirus [types 16 and 18] Recombinant Vaccine).

Gardasil was first approved by the U.S. Food and Drug Administration (FDA) in 2006 and protects against four types of HPV: 6, 11, 16, and 18. Types 16 and 18 are linked with cervical cancer as well as certain other types of cancer, and types 6 and 11 cause most cases of genital warts. Gardasil is approved for use in boys and girls between the ages of nine and 26 years. In boys Gardasil is approved for prevention of genital warts. In girls it is approved for prevention of genital warts as well as cancer or precancer of the cervix, vulva, and vagina.

Cervarix was first approved by the FDA in 2009 and protects against two types of HPV: 16 and 18. Cervarix is approved for use in girls between the ages of 10 and 25 years for the prevention of cancer or precancer of the cervix.

As more data become available, these vaccines may be approved for additional purposes or for use in additional populations.

It’s important to keep in mind that these vaccines are intended to prevent infection with certain types of HPV. They do not treat existing HPV infections. As a result, the vaccines are likely to be most effective when given before an individual becomes sexually active. Furthermore, because neither vaccine protects against all high-risk types of HPV, they do not completely eliminate the risk of HPV-related cancer.

References

[1]. Gillison ML, Chaturvedi AK, Lowy DR. HPV prophylactic vaccines and the potential prevention of noncervical cancers in both men and women. Cancer. 2008;113(10 Suppl):3036-46.

[2]. D’Souza G, Agrawal Y, Halpern J, Bodison S, Gillison ML. Oral sexual behaviors associated with prevalent oral human papillomavirus infection. Journal of Infectious Diseases. 2009;199(9):1263-69.

[3]. Ryerson AB, Peters ES, Coughlin SS, et al. Burden of potentially human papillomavirus-associated cancers of the oropharynx and oral cavity in the US, 1998-2003. Cancer. 2008;113(10 Suppl):2901-9.

[4]. Kreimer AR, Clifford GM, Boyle P, Franceschi S. Human papillomavirus types in head and neck squamous cell carcinomas worldwide: a systematic review. Cancer Epidemiology, Biomarkers, and Prevention. 2005;14(2):467-75.

[5]. D’Souza G, Kreimer AR, Viscidi R, et al. Case-control study of human papillomavirus and oropharyngeal cancer. New England Journal of Medicine. 2007;356(19):1944-56.

[6]. Sturgis EM, Cinciripini PM. Trends in head and neck cancer incidence in relation to smoking prevalence: an emerging epidemic of human papillomavirus-associated cancers? Cancer. 2007;110(7):1429-35.

[7]. Gillison ML, Harris J, Westraet W, et al. Survival outcomes by tumor human papillomavirus (HPV) status in Stage III-IV oropharyngeal cancer (OPC) in RTOG 0129. Paper presented at: 45th Annual Meeting of the American Society of Clinical Oncology; May 29–June 2, 2009; Orlando, Florida. Abstract #6003.

[8]. Gillison ML. Human papillomavirus-related diseases: oropharynx cancers and potential implications for adolescent HPV vaccination. Journal of Adolescent Health. 2008;43(4 Suppl):S52-S60.