Listen to the Cancer.Net Podcast: HPV and Cancer [1], adapted from this content.

Human papillomavirus (HPV) is a virus that is most commonly transmitted during sex and direct skin-to-skin contact. There are more than 100 different types or strains of HPV. Most men and women aren't aware they have an HPV infection because they don't develop any symptoms or health problems. But in some cases, certain types of HPV can cause warts (noncancerous, abnormal growths on the skin) in various parts of the body. In other cases, specific HPV types can cause precancerous lesions (areas of abnormal tissue) or cancer.

How HPV Spreads

Approximately 60 types of HPV have the potential to cause common warts, which grow on areas such as the hands and feet. Approximately 40 of the viruses are called “genital type” HPVs. These viruses are spread from person to person when genitals come into contact, usually during vaginal or anal sex. The virus can also be transmitted through oral sex. HPV is the most common sexually transmitted disease in the United States.

Genital HPV types can infect the genital area of women, including the vulva (outer portion of the vagina), the lining of the vagina, and the cervix (the lower, narrow part of a woman's uterus), as well as the genital area of men, including the penis. In both men and women, genital HPV can infect the anus and some areas of the head and neck. Sometimes “low-risk” strains of genital HPVs, most commonly HPV-6 or HPV-11, can cause genital warts or lesions to form on or around these locations. The growths can vary in size, shape, and number, and rarely lead to cancer.

HPV-Related Cancers

Genital HPV types that are more likely to cause cancer are referred to as “high-risk” HPVs. Usually the immune system of a man or woman infected with low-risk or high-risk HPV gets rid of the infection and the virus does no harm. However, some people develop a persistent (lasting) infection that slowly, often over many years, causes changes to normal cells that lead to precancerous lesions or cancer.

Cancers associated with HPV include:

Cervical cancer. Essentially all cancers of the cervix are caused by HPV infection. Whether a woman who is infected with HPV will develop cervical cancer depends on a number of factors, including the type of HPV. Of the cervical cancers related to HPV, about 70% are caused by two strains, HPV-16 or HPV-18. In women who have HPV, smoking may increase the risk of cervical cancer. Although almost all cervical cancers are caused by HPV, it is important to remember that most genital HPV infections won't cause cancer.

Oral cancer. HPV can cause oral cancer (cancer of the mouth and tongue) and oropharyngeal cancer (cancer of the oropharynx, the middle part of the throat located from the tonsils to the tip of the voice box) in men and women. These HPV-related cancers are increasing steadily in men. In fact, the HPV virus now causes as many cancers of the upper throat in men as tobacco and alcohol use, according to a recent study. Changes in sexual behavior, including an increase in oral sex, may be one reason for the rise.

Other cancers. HPV is also associated with less common cancers. Almost one-half of cancers of the vulva are associated with HPV. The types of HPV that cause cervical cancer are also related to anal cancer. High-risk HPV types are also associated with vaginal cancer and penile cancer.

Treatment

There is no cure for HPV. However, most HPV infections simply go away over time or are weakened to the point where they do not affect the body. An infection that is not active may become active when a person's immune system is weakened by treatment for other diseases, such as cancer.

Health problems caused by HPV can be treated. Warts and precancerous lesions can be removed through cryotherapy (freezing); loop electrosurgical excision procedure (LEEP), which uses electric current to remove abnormal tissue, or surgery. Topical medications (such as creams that are applied directly to the skin) can also be prescribed for genital warts. However, removing genital warts does not mean a person no longer has HPV. Warts may return later because the virus may still be living in cells. A person with HPV who does not have any visible warts can still infect a sexual partner with the virus.

Prevention Strategies

There are ways to reduce your risk of HPV infection, including receiving an HPV vaccine. Limiting your number of sex partners is another way to reduce your risk because having many partners increases the risk of HPV infection. Using a condom cannot fully protect you from HPV during sex.

The U.S. Food and Drug Administration (FDA) has approved two vaccines that help prevent infection with HPV: Gardasil and Cervarix. Gardasil helps prevent infection from the two HPVs known to cause most cervical cancers and precancerous lesions in the cervix. The vaccine also prevents against the two low-risk HPVs known to cause 90% of genital warts. Gardasil is approved for the prevention of cervical, vaginal, vulvar in girls and women ages nine to 26. It is also approved to prevent anal cancer in women and men and genital warts in men and boys in the same age range. Meanwhile, Cervarix is approved for the prevention of cervical cancer in girls and women ages 10 to 25.

Because a vaccine can only prevent infection, not cure an existing one, it is important that it be given to people before they become sexually active. People who are already sexually active and who may already be infected with HPV should talk with their doctor. The vaccine may protect them from strains of HPV that they don't have.

In addition to the vaccine, women should protect themselves by having Pap tests [2], the most common test to help detect cervical cancer. Pap tests can find precancerous cells that can be removed before they turn into cancer. Researchers have found that combining a Pap test with a test designed to detect HPV in women provides the most accurate results. A woman should talk with her doctor about having a Pap test and possibly an HPV test.

Questions to Ask Your Doctor

Learn more about HPV, including your risk of infection and ways to help prevent it, by asking your doctor the following questions:

• What is my risk of getting HPV?
• How can I reduce my risk of getting HPV?
• Can I get genital HPV without having sex?
• What are some of the signs and symptoms of HPV?
• How soon after sex do HPV symptoms appear?
• Should I be tested to see if I have HPV?
• Should I receive the HPV vaccine? Why or why not?
• Is the HPV vaccine safe? What are the side effects?
• How is the vaccine given? Is more than one shot needed?
• How long does the HPV vaccine last?
• Does my health insurance cover the cost of the HPV vaccine?
• I'm pregnant and have HPV. Can it harm my baby?

More Information

ASCO Expert Corner: HPV Vaccination for Cervical Cancer [3]

Cervical Cancer [4]

Head and Neck Cancer [5]

Additional Resources

Centers for Disease Control and Prevention: Human Papillomavirus Infection [6]

National Cancer Institute: Human Papillomaviruses and Cancer [7]

Food and Drug Administration: Human Papillomavirus Infection Vaccines [8]

Last Updated: March 16, 2011