Human Papilloma Virus (HPV) is the most common sexually transmitted disease in the United States. Over 79 million people are currently infected and it is estimated that 14 million people become infected annually. Seventy five percent of all new infections occur in young adults between the ages of 15-24.
Risk factors for HPV transmission are related to sexual behavior, such as the number of sexual partners, the onset of sexual activity and the type of sexual activity. In the majority of individuals, HPV is a transient infection, which spontaneously resolves within two years. It is unclear why the majority of people are able to mount an adequate immune response and clear the infection, while others develop pre-cancerous and cancerous lesions.
There are over 100 subtypes of HPV. Most low-risk subtypes of HPV infection may manifest as warts; other types can cause abnormal throat growths called papillomas. However, other high-risk subtypes (particularly type 16 and 18) of HPV can cause pre-cancerous cells in the cervix that can lead to cervical cancer.
In 2013, it is predicted that there will be over 12,000 new cases of cervical cancer, and high-risk subtypes of HPV are responsible for 99 percent of these cancers. High-risk subtype HPV also causes other anogenital cancers including vaginal, vulva, penile and anal cancer.
More recently, these same high-risk subtypes of human papillomavirus have been implicated in the alarming increase in cancers of the oropharynx (tongue, back of throat and tonsil area).
In the past 40 years there has been a steady decline in the incidence of head and neck cancers. Public health officials were delighted that as a direct result of people successfully curtailing tobacco use, cancers of the head and neck also decreased. However, it became clear that cancers in one area of the head, the oropharynx, were on the rise at 1 percent a year since 1971. The incidence of these cancers in men, particularly, was increasing at an alarming pace of 5 percent a year.
Further investigation revealed that in the majority of these particular head and neck cancers, a high-risk HPV, mostly type 16, had infected the tissues of the back of the throat and were responsible in some studies for up to 85 percent of the oropharyngeal cancers currently diagnosed throughout the United States. Studies again indicated that sexual activity – in particular, multiple vaginal and oral sex partners – was associated with an increase in the risk of developing HPV in the oropharynx.
This summer the Costa Rican HPV Vaccine Trial reported four-year findings of evaluating the vaccine Cervarix in preventing cervical cancer and also high-risk type 16 and 18 HPV infections in the oral cavity. Over 7,400 women participated, and half of the women received the HPV 16/18 vaccine and the remaining women received a control vaccine. At four years the trial indicated the HPV16/18 vaccine reduced oral infections with HPV 16/18 by 93 percent.
There is currently no treatment for an HPV infection and for most no signs or symptoms of infection. There are important methods to prevent HPV transmission, which include routine and consistent condom use or abstaining from sexual activity.
The vast majority of cervical cancer cases can be prevented through evaluation of the cervix with Pap test screening. All women should begin screening at the age of 21. The American Cancer Society also recommends screening every three years under the age of 30. Women over the age of 30 should undergo screening every five years with Pap and HPV test.
There are currently no screening recommendations for early detection of an oropharyngeal cancer; however signs and symptoms include a painless neck mass, sore throat and ear pain. There are now vaccines available to prevent the development of genital warts, cancers of the cervix and genitalia.
The same high-risk HPV has been implicated in the alarming increase in tongue and tonsil cancers. The Costa Rican trial is the first to indicate the efficacy of these vaccines in preventing HPV infection in the cervix and oral cavity. These vaccines are not effective once a person is infected; therefore, vaccination must occur before sexual activity.
The importance of the dramatic rise in cancers of the oropharynx and the known risk of cancers of the cervix and genital area make these vaccines an important discussion with your pediatrician and gynecologist. Knowledge is power and preventing disease is the ultimate goal for our young adults.
Lannis Hall, MD, MPH, is director of radiation oncology at Siteman Cancer Center, Barnes–Jewish Saint Peters Hospital, and clinical trials outreach leader for the Program to Eliminate Cancer Disparities at Washington University School of Medicine.
