All About HPV
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What is HPV?
Human papillomaviruses (HPV) are common viruses that can cause warts, also called papillomas. There are more than 200 types (or strains) of HPV. About 40 of these strains can be spread through sexual contact. Most strains of HPV do not cause problems. However, many can cause genital warts and 12 types are known to cause cancer. Genital HPV infection is very common, affecting about 80 million Americans in their lifetime. About 85 out of 100 people who are sexually active have a chance of being infected with HPV at some point in their lives.
HPV can infect the skin, genitals, and oropharynx (mouth/throat), and spread through genital skin-to-skin contact, masturbation, and oral, vaginal, or anal sex with another person (of either sex) who has HPV. A person who has HPV will often not have any symptoms from the virus. Many people do not know they have HPV. Many high-risk HPV infections go away on their own (they are cleared by the immune system, often within 2 years), and therefore do not lead to cancer.
Am I at risk for HPV Infection?
Risk factors include
- Sexual activity. Vaginal intercourse and anal penetration appear to be the easiest ways to spread the infection, but they are not necessary to transmit the virus. Genital skin-to-skin contact and oral sex can spread the virus as well. Masturbation with a partner may even transmit the virus as HPV can be detected on the fingertips of women and men who have genital warts.
- Having many sexual partners (or a partner with a history of many sexual partners).
- Early age at first intercourse (vaginal or anal).
- History of other sexually transmitted infections.
High-Risk Versus Low-Risk Strains of HPV
The different strains of HPV are either low-risk or high-risk.
- Low-risk HPV (including HPV types 6 and 11) can cause genital warts—or no symptoms at all.
- High-risk HPV (including HPV types 16 and 18) causes about 70 out of 100 cases of cervical cancer.
What cancers can be caused by HPV?
- Cervical cancer.
- Vaginal cancer.
- Vulvar cancer.
- Anal cancer.
- Head and neck cancer- most commonly oropharynx cancer (areas in the back of the mouth, the base of the tongue, and the tonsils).
Clearing the Infection
We don't know why some people's immune systems can clear the HPV infection and others cannot. Smoking is one thing that increases the chance that the immune system will not clear the virus. Other factors in women (as this is the population in whom most of the research has been done) include multiple childbirths, long-term oral contraceptive use, and possibly chronic inflammation, but we don't know exactly why these factors increase risk.
Since most people's immune systems can clear the virus, the risk of transmission may be lower for couples who wait longer to have sexual relations or have long periods of abstinence between relationships, giving their bodies time to clear any infection before entering a new sexual relationship. Risk is lower for long-term, monogamous (only having one partner) couples as well. HPV infection lasts about 1 year in women and may be as short as 6 months in men, but this may vary depending on the strain.
Most infections will clear on their own, but people with active infections that keep going after 2 years are at the highest risk of getting cancer. The key is that these women (as we do not currently test for HPV in cis men) need to have recommended follow-up and annual Pap testing so that any pre-cancerous changes are found early.
Prevention: HPV Vaccines
The HPV vaccine protects against infection by certain strains of HPV that can cause cervical, vaginal, vulvar, and anal cancer and genital warts. There are 3 HPV vaccines made in the United States, but only Gardasil 9 is available.
- Ceravix protects against HPV 16 and 18.
- Gardasil protects against HPV strains 16, 18, 6 and 11.
- Gardasil 9 protects against HPV 6, 11, 16, 18, 31, 33, 45, 52, and 58.
This vaccine does not treat cancer. Individuals who get the vaccine should still have Pap testing when your provider recommends it because it does not protect against all types of HPV. HPV-16 and HPV-18 are responsible for most cases of cervical cancer. HPV-6 and HPV-11, cause about 90 out of 100 cases of genital warts.
HPV vaccines are recommended for all individuals ages 12 to 26. It is given in 2 or 3 doses, depending on your age when it is started. The US Food & Drug Administration has approved the vaccine for use in individuals up to age 45, but most insurance companies will not cover it beyond age 26 and it is not recommended for routine use after age 26 by any professional organizations. The most common side effects after the injection are fainting, dizziness, nausea, headache, and skin reactions at the site where the shot was given.
- The HPV vaccine can prevent HPV strains 16 and 18 and cervical cancer, and can also prevent 49 out of 100 cases of vulvar cancer.
- 55 out of 100 cases of vaginal cancer.
- 79 out of 100 cases of anal cancer.
The HPV vaccine does not protect against all types of HPV or other sexually transmitted infections, such as HIV.
HPV Screening and Cancer Prevention
Cervical cancer is the fourth most common cancer in women worldwide, with about 660,000 new cases per year, most in developing countries. There are about 13,000 cases diagnosed in the US every year. Screening with Pap testing has resulted in lower rates of cervical cancer in many developed nations, but countries with fewer resources lag far behind in lowering the incidence of this disease.
The HPV vaccine does not protect against all types of HPV that lead to cervical cancer, therefore women should still receive regular screening, even after receiving the vaccine.
There are many organizations that make recommendations regarding cervical cancer screening and they may vary. It is important to talk to your provider about what type of screening is right for you and when you should have the tests done. You can learn more about the cervical cancer screening guidelines in this article, The Pap Test: Cervical Changes and Further Testing.
Women who are at high risk for cervical cancer may need to be screened more often. Women at high risk might include those with HIV infection, organ transplant, or in-utero exposure to the drug DES. They should talk with their healthcare provider for specific recommendations.
There is no approved screening test to find early signs of penile, vulvar, head-and-neck, or anal cancer. Having a routine exam of these areas and telling your healthcare provider about any changes is recommended. Men who have receptive anal intercourse or women with cervical dysplasia or HIV may benefit from anal pap screening. Learn more about this screening on the UCSF anal neoplasia research & treatment group website.
Talk with your provider about HPV testing, vaccines, and cancer risk reduction.