Human papilloma virus (HPV), commonly known as the virus that causes genital warts and cervical cancer in women, is increasingly being recognized as a cause of infections that colonize the back of the mouth (throat), including the tongue base and tonsils.
What is HPV?
HPV is a sexually transmitted virus. There are more than 40 subtypes of HPV that can infect the genital area and the throat (tonsillar HPV).
How common is HPV infection of the throat?
A recent study found that 7% of Americans 14 to 69 years old are infected with tonsillar HPV. The same study found that the prevalence has increased significantly over the past three decades, and that more men than women have oral HPV infection.
The most frequent subtype of tonsillar HPV detected is HPV-16, a high-risk subtype of HPV for oropharyngeal (mouth and pharynx) cancer. About two thirds of oropharyngeal cancers have HPV DNA in them. Infection with HPV-16 occurs in about 1% of men and women.
How is oral HPV acquired?
Evidence strongly suggests that tonsillar HPV is predominantly transmitted by sexual contact. An increase in oral sex is suspected as the cause of the increase in the prevalence of tonsillar HPV infection, although several sexual behaviors seem to be related to oral HPV prevalence. The risk of infection increases with an increasing number of lifetime or recent sexual partners for any type of sexual behavior (ie, vaginal sex, oral sex). With 20 or more lifetime sexual partners, the prevalence of oral HPV infection reaches 20%. Smokers are also at greater risk than nonsmokers, with current heavy smokers at particularly high risk.
What are the signs and symptoms of HPV infection?
Most people with oral HPV infections have no symptoms and therefore do not realize that they are infected and can transmit the virus to a partner.
What are the consequences of tonsillar HPV infection?
Tonsillar HPV infection can cause oropharyngeal cancer. An increase in the incidence of oropharyngeal cancer has paralleled the increased prevalence of tonsillar HPV infection. However, the vast majority of people with tonsillar HPV infections do not develop cancer because the subtypes of HPV with which they are infected are not linked to development of cancer. Although millions of Americans have tonsillar HPV, fewer than 15,000 get HPV-positive oropharyngeal cancers annually.
Many oropharyngeal cancers are not related to HPV infection but rather with tobacco and alcohol use. People with HPV-positive oropharyngeal cancers tend to be younger and are less likely to be smokers and drinkers.
Are there any signs that are specific for HPV-positive oral cancer?
The first sign is often having trouble with swallowing. Other signs are
- coughing up blood
- a lump on the neck or in the cheek, or
- hoarseness that doesn’t go away
Unfortunately, these are late signs of the disease.
Other potential signs and symptoms of oral cancers are
- sore throat
- a white or red patch on the tonsils
- jaw pain or swelling, and
- numbness of the tongue, among others
These signs don’t necessarily mean that you have cancer, but if any signs are present for longer than 2 weeks, you should see your doctor.
How is tonsillar HPV infection found?
There is no test that can find early signs of HPV infection of the throat. Some cancerous or precancerous tonsillar HPV lesions may be detected during screening or examination by a dentist or doctor, but most are found by testing in persons who already have signs or symptoms.
To inspect hard-to-see areas of the throat, larynx (voice box), and the base of the tongue, doctors may use instruments called laryngoscopes or pharyngoscopes together with small mirrors. For certain structures in the throat that can’t be seen easily with mirrors, flexible laryngoscopes and pharyngoscopes can penetrate deeper to permit the doctor to see them directly.
The doctor may want to perform a biopsy of areas that look suspicious for cancer. A biopsy is a small sample of cells taken with a thin, hollow needle. The cells are then viewed under a microscope to look for signs of cancer. Biopsy samples from throat cancers may be tested for the presence of HPV DNA. The presence of HPV DNA signals a cancer that is more responsive to treatment than one that is HPV-negative.
Can tonsillar HPV infection be prevented?
The only surefire way to prevent it is to abstain from sex. Although vaccines have been developed that reduce the risk of infection with subtypes of HPV that are known to cause cervical cancer, their effect in preventing oropharyngeal cancers linked to the same HPV subtypes is unknown. These vaccines are prophylactic vaccines in that they may prevent HPV infection (they do not treat an existing infection), and thus are recommended before a person is sexually active.
The Centers for Disease Control and Prevention (CDC) recommends that all 11- or 12-year-old girls receive the HPV vaccine to protect against cervical cancer, and that females 13 to 26 years old be vaccinated if they have not received the HPV vaccine when they were younger. The CDC also recommends the HPV vaccine for all boys aged 11 or 12 years, and for males 13 to 21 years old who did not receive the vaccine when they were younger. All men may receive the vaccine through age 26. The HPV vaccine is also recommended for any man who has sex with men and men with compromised immune systems through age 26 (if not vaccinated at a younger age).
Talk to your doctor to find out if getting vaccinated is right for you.
How is an oral HPV-positive cancer treated?
The treatment of choice is either chemotherapy or radiation therapy up front, or surgery followed by radiation therapy with or without the addition of chemotherapy. Radiation therapy involves the delivery of high levels of radiation to kill cancer cells or to keep them from growing and dividing. Chemotherapy is a cancer treatment used most often to describe drugs that kill cancer cells directly.
After surgery to remove an oropharyngeal cancer, further surgery may be needed to reconstruct parts of the oral cavity that were removed as part of the treatment.
What is the prognosis?
Fortunately, HPV-positive oropharyngeal cancers have better outcomes and fewer relapses after treatment than HPV-negative cancers. In patients with oropharyngeal cancer treated with radiation and chemotherapy, survival was longer among those with HPV-positive tumors vs. HPV-negative tumors.
- Ang KK, Harris J, Wheeler R, et al. Human papillomavirus and survival of patients with oropharyngeal cancer. N Engl J Med 2010;363:24-35.
- Gillison ML, Broutian T, Pickard RKL, et al. Prevalence of oral HPV infection in the United States, 2009-2010. JAMA 2012;307:693-703.
- Chaturvedi AK, Engles EA, Pfieffer RM, et al. Human papillomavirus and the rising oropharyngeal cancer incidence in the United States. J Clin Oncol 2011;29:4294-4301.
- What's new in oral cavity and oropharyngeal cancer research and treatment? www.cancer.org Accessed 2/28/2012
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