Many people know about the link between HPV and cervical cancer, but did you know that HPV also causes at least five other cancers?
On this page we explain which types of cancers are associated with HPV, how HPV works to cause cancer, and how many of these cancers occur in the US and UK every year. We also discuss steps that you can take to protect yourself and your loved ones from HPV-associated cancer. Finally, we provide a timeline of HPV and cancer to show you how far we have come, and how far we still have to go.
WHAT IS THE LINK BETWEEN HPV AND CANCER?
Infection with the human papillomavirus (HPV) causes 5% of all cancers worldwide.
The majority of HPV-associated cancers are linked to just two types of HPV: types 16 and 18. There are about 16 high-risk types that have been identified, and there are over 100 different types of HPV overall. 40 HPV strains are sexually transmitted. The term ‘high-risk’ means that these types of HPV are more likely than other types to cause cancer.
Both low-risk and high-risk HPV infections can disappear on their own without causing any damage to the body. The symptoms are abnormal changes in cells and are usually very mild. They often go away even if left untreated. The immune system is often able to attack the virus before it has a chance to cause long-term infection. In fact, people can be totally unaware that they even had symptoms or HPV.
Some high-risk HPV infections can remain in the body for years, however. These longer-lasting infections can lead to more serious changes in cells that may progress to cancer if they are not found and treated. Please see our Anal Precancer information page for more details about the various types of anal precancer specifically.
WHAT CANCERS ARE ASSOCIATED WITH HPV?
HPV causes a majority of anal cancer (93%), cervical cancer (96%), oropharyngeal cancer (63%), vaginal cancer (64%) and vulvar cancer (51%), as well as some penile cancer (36%). Studies have also found HPV DNA in tumours of the oral cavity and larynx. Emerging studies also have found HPV DNA in lung tumours.
HPV-related cancers are on the rise in general. The National Cancer Institute (NCI) reports that incidences (new cases) of both anal and oropharyngeal cancers are increasing. It is estimated that by 2020 there will be more HPV-associated oropharyngeal cancer diagnoses than cervical cancer in high-income countries like the US and UK.
According to the Centers for Disease Control and Prevention (CDC) every year in the US, 30,700 people are diagnosed with a cancer caused by HPV.
A recent study [Saraiya et al. (2015). US assessment of HPV types in cancers: implications for current and 9-valent HPV vaccines. Journal of the National Cancer Institute; 107(6)] gave the following HPV-associated cancer estimations based on a review of US Cancer Registries from 2008-2010:
In the US:
- HPV-associated anal cancer affects around 5,530 women and 2,770 men every year.
- The most common cancer attributed to HPV in US women is cervical cancer, with 11,886 HPV-attributable cases being diagnosed every year.
- The most common HPV-attributed cancer in men is oropharyngeal cancer with roughly 18,226 HPV-attributable cases diagnosed in men and women every year. Oropharyngeal cancer is sometimes called head and neck cancer. Some oral cavity and larynx cancers may also be connected to HPV.
- HPV-associated penile cancer affects around 1,269 men every year.
- There are about 846 HPV-associated vaginal cancer diagnoses every year.
- There are 3,934 HPV-associated vulvar cancer diagnoses every year.
Note that these numbers do not reflect the overall numbers of these specific cancers diagnosed every year, simply the HPV-related ones. Over the last few decades, scientists have discovered that more cancers in these sites are related to HPV.
In the UK, the following number of HPV-associated cancer cases were diagnosed in 2015:
- 910 women were diagnosed with HPV-associated anal cancer.
- 437 men were diagnosed with HPV-associated anal cancer.
- 3,126 women were diagnosed with HPV-associated cervical cancer.
- 6,132 men and 2,701 women were diagnosed with HPV-associated head and neck cancer.
- 401 men were diagnosed with HPV-associated penile cancer.
- 174 women were diagnosed with HPV-associated vaginal cancer.
- 924 women were diagnosed with HPV-associated vulvar cancer.
HOW DO HIGH-RISK TYPES OF HPV CAUSE CANCER?
All types of HPV infect squamous epithelial cells, which are the cells that cover the skin and mucous membranes. Once the infection has occurred, the virus is able to enter the cell and make proteins. Two of the proteins made by high-risk types interfere with normal cell functioning that prevents excessive growth. This interference causes the cell to grow uncontrollably.
In many cases, the infected cell is recognised by the body’s immune system, which will prevent the virus from doing serious harm. If the immune system does not kick in, however, the infected cells will continue to mutate and divide, causing more abnormal cells. This can lead to even more uncontrolled growth.
If growth continues, lesions (damaged tissue) develop which can eventually turn into tumours (cancer). Researchers believe that it can take from 10 to 20 years or longer for a new infection with high-risk HPV to develop into cancer.
HPV types that cause cancer include 16, 18, 31, 33, 34, 35, 39, 45, 51, 52, 56, 58, 59, 66, 68 and 70. Types 16 and 18 are the most common.
HOW MANY CANCERS WORLDWIDE ARE LINKED TO THE MOST COMMON HPV TYPES, HPV 16 AND 18?
HPV 16 and 18 are the most common and most high-risk types of the virus. Of all cancers probably caused by HPV worldwide, the following are linked to these two specific types:
- 70% of cervical cancer
- 92% of anal cancer
- 89% of oropharyngeal cancer
- 63% of penile cancer
- 80% of vaginal cancer
- 80% of vulvar cancer
HOW CAN I PREVENT GETTING HPV-ASSOCIATED CANCER?
Three vaccines are approved to protect people from the high-risk HPV strains that cause the most cancers. Two of these vaccines are approved for use in all males and females while one is approved only for females.
All male and female children in the US under 26 are recommended to receive the HPV vaccine. Routine vaccination is recommended at the ages of 11 or 12 during their pre-teen check-up, but the vaccination series can begin as young as 9.
In the UK, all female children are recommended to receive the vaccine at 12 and 13. Please see our Vaccination page to learn more about these vaccines and how they are effective in the fight against cancer.
UNDERSTAND HPV TRANSMISSION
HPV is transmitted through skin-to-skin contact. In addition to immunisation against various strains of the virus, staying safe from HPV-associated cancers involves protecting yourself from HPV infection. To do so means avoiding all intimate manual and genital contact with another person for an entire lifetime.
HPV is transmitted through multiple forms of sexual contact. HPV has even been found in young women and men who report no-to-limited penetrative sexual activity, reaffirming the importance of vaccination prior to any form of sexual activity. HPV transmission is also possible through all forms of sex, including oral sex. Emerging studies show that there may also be oral-to-oral transmission of HPV, but more studies are needed to show whether this transmission is possible through kissing.
Since most people will have at least one intimate partner at some point in their lives, nearly every person will be exposed to HPV. Someone with one life partner can still get HPV. However, a sexually monogamous relationship with an uninfected partner will likely reduce your chance of exposure to the virus. Most people are unaware that they are – or were ever – infected.
Even latex condoms, though helpful at reducing exposure, are not 100% reliable at preventing infection. Areas of skin not covered by the condom can still transmit the virus to a sexual partner.
SCREENING AND TESTING
Cancers can also be prevented with routine screening and follow up. The only routine screening method, and the most commonly known, is the cervical pap smear. However, if you feel or see abnormal changes in other parts of your anogenital or oral region, see your medical provider for further advice.
Cervical pap tests are recommended to look for abnormal cells on the cervix caused by HPV. Any abnormalities found can then be removed before they have a chance to get worse. In addition to the cervical pap test, the FDA has also recently approved HPV DNA tests for women over 25. These are not blood tests but look for HPV DNA in cervical cells. These can help determine whether a woman has any of the high-risk strains. Her physician can then recommend an appropriate course of action to prevent cancer.
Unfortunately, there is no routine standard test or screening process to detect HPV in men. There are also no standard screening protocols to detect HPV in locations in women other than the cervix. However, individuals who feel they may be at risk may want to consult their providers regarding screening options that exist but are not administered routinely.
Efforts are underway to study the best prevention and treatment methods for precancer in other parts of the anogenital area and the head and neck as the cervix is the only location routinely screened for abnormal changes related to HPV.
We are helping to lead the effort to establish better prevention options for anal precancer for men and women. There are tools available to detect anal precancer such as the anal pap, high-resolution anoscopy and DREs, but these are not yet included in official screening guidelines. We are working to advocate for expanded guidelines to other HPV-affected sites as quickly as we can to augment the already approved cervical precancer screening guidelines. Updating HPV-associated precancer screening guidelines will help to catch cancer early in thousands of people.
Please visit our Anal Precancer page for more information about methods that have been used effectively in screening for anal cancer.
KNOW THE RISK FACTORS FOR HPV DEVELOPING INTO CANCER, AND HOW THESE AFFECT YOU
It is important to remember that infection with HPV does NOT mean that a cancer diagnosis is inevitable. HPV is the most common sexually transmitted disease in the United States with about 80 million people currently infected and nearly every person becomes infected at some point in their lifetime.
However, certain risk factors, such as smoking or a compromised immune system, can increase the chance that an HPV infection will develop into cancer. You are also more likely to be diagnosed with an HPV-associated cancer if you have already had one. For example, a risk factor for HPV-associated vulvar cancer is a previous diagnosis of HPV-associated cervical cancer.
Please make sure to discuss your risk factors with your doctor, and ensure that you receive timely and adequate screening and medical care when necessary.
WHY ARE WE ONLY LEARNING ABOUT THE LINK BETWEEN HPV AND CANCER NOW?
Researchers have actually suspected that cervical cancer is linked to a sexually transmitted mechanism since the 19th century. They only discovered the specific connection between HPV and cervical cancer in the 1980s, however, when researchers in Germany found HPV in the majority of cervical tumours.
Still, not many people know about HPV or its association with cancer. This is partially due to lack of education about this issue and poor communication about it to the public. It is very common to only find out about HPV after a person has received an abnormal pap test or even a cancer diagnosis.
This is something that the Anal Cancer Foundation is working to change. We need to spread the word about the link between HPV and cancer to help prevent future tragedies. Now that we have a vaccination to prevent infection with the main cancer-causing types of HPV, we can put an end to these cancers!
TIMELINE OF HPV AND CANCER
Dr. George Papanicolaou discovers that cervical cancer cells can be detected with a vaginal smear test. This paves the way for him to produce the world’s first cervical cancer screening test, now known as the ‘pap’ smear, which swipes cells from the cervix, not the vagina.
The pap is introduced to physicians’ offices. It helps doctors detect and treat cervical cancer and precancer before it can spread to other organs. Over the next few decades, the pap test helps prevents thousands of deaths in high-income countries. Since its initial introduction, the pap smear has resulted in an approximately 70% decrease in cervical cancer rates in the US.
German researchers discover that most cervical pre-cancers and cancers contain HPV. They specifically find HPV types 16 or 18. Other types of HPV are later linked to cervical cancer, but 16 and 18 are considered the most risky. In the 1980’s, HPV’s link to anal, penile, vaginal and vulvar cancers is also discovered.
Some of the first studies linking HPV types 16 and 18 to cancers of the oropharyngeal region are published.
Widespread, Medicare-subsidised screening for cervical cancer in women over the age of 65 leads to a 19% reduction in diagnoses of this cancer from 1990. Screening has allowed greater detection of precancerous lesions, leading to earlier treatment, halting the development of cancer.
An HPV DNA test is approved by the FDA. It is different than the pap smear because it is looking for the presence of high-risk HPV DNA within the DNA of the cell using a specific machine, whereas the pap smear looks for abnormal changes to the cell that can be seen though a microscope. The HPV DNA test is able to identify DNA from several high-risk HPV types. The HPV test can detect HPV infections that have the potential to cause cell abnormalities, sometimes before these abnormalities are even visible.
The HPV test is currently approved for use in women over 25 without needing a concurrent pap test, as well as for women of any age who have had an abnormal pap test. Used alone, the HPV test will help determine the need for additional testing or screening. The HPV DNA test is better at detecting pre-cancers than the pap test, but also gives more false positives. In combination, the DNA and pap tests are excellent tools to detect pre-cancer risk. In 2014, the FDA approved the HPV DNA test to be used alone to detect precancer and determine the need for additional testing.
The FDA approves Gardasil, the first vaccine that protects against HPV. This first version of Gardasil prevents infection with HPV 16 and 18, the two high-risk strains that cause most anal, vaginal, vulvar, oropharyngeal, penile, and cervical cancers. It is approved for use in females and males ages 9-26, however, it is only routinely recommended for girls at this time. It is permissively recommended for boys in 2009.
A second vaccine against HPV 16 and 18 called Cervarix is approved for females aged 9-25 in the UK.
Cervarix is approved for females ages 10-25 in the US. Gardasil is also approved for use in the US in males ages 9-26 to prevent genital warts.
The FDA approves Gardasil for the prevention of anal cancer. The Anal Cancer Foundation testified before the FDA regarding the importance of preventing anal cancer.
In the US, Gardasil is routinely recommended for all children – boys as well as girls – at the age of 11-12. This means it is recommended for all children at their preteen check-up alongside other pre-teen vaccines, Tdap and Meningococcal. Catch-up vaccine is recommended up to the age of 21 for boys and 26 for girls who did not already receive the vaccine. It is recommended that men who have sex with men and immunocompromised men should also be vaccinated until the age of 26. During hearings held by the CDC, the Anal Cancer Foundation led a coalition of organisations to submit multiple testimonies in support of expanding the vaccine to protect all children against HPV and the cancers it causes. Read those testimonies here and here.
The UK Department of Health approves Gardasil and it replaces Cervarix in the national immunisation program.
The President’s Cancer Panel releases a report urging an increase in vaccine uptake. The panel notes that full vaccine coverage amongst adolescent girls was only at 33.4% in 2012. Amongst boys, coverage was even worse, at only 6.8%. The Panel calls these low rates “a serious threat to progress against cancer” The Panel stated: “By supporting vaccination as an urgent national and global health priority, the US National Cancer Program has an unprecedented opportunity to contribute to preventing millions of avoidable cancers and other conditions in men and women worldwide”.
The ANCHOR study begins. This study is designed to determine whether routine screening and treatment of high-grade squamous intraepithelial lesions (HSIL for short) in HIV+ men and women is an effective method of preventing anal cancer. This study is still actively recruiting participants. The Anal Cancer Foundation hopes that one day anal pap smears will become as routine as cervical paps are today. The ANCHOR study is the first step towards that day and saving thousands of lives a year. Read our letters to the National Cancer Institute in support of this study here and here.
Also in 2014, the FDA approved the use of a third vaccine, Gardasil 9, for use in females ages 9-26 and males aged 9-15. The ‘9’ was added as this vaccine provides protection against nine different strains of HPV: types 6, 11, 16, 18, 31, 33, 45, 52 and 58. Like Gardasil, Gardasil 9 protects against anal, cervical, vulvar and vaginal cancers; and types 6 and 11 to protect against genital warts. Please see our Vaccination page for more information on this recent addition to the options for protection against HPV. It is expected that the recommendation will be expanded to include all girls and boys up to 26 in late 2015 or 2016.
The Joint Committee on Vaccination and Immunisation (JCVI) recommended that boys should also be included in the UK HPV vaccination program from September 2019.