HPV causes six types of cancer: cervical, oropharyngeal (back of the throat), anal, penile, vaginal, and vulvar. Together, these account for roughly 39,300 new cancer cases each year in the United States alone. Not every HPV infection leads to cancer, but persistent infection with certain high-risk strains can trigger cell changes that, over years or decades, become malignant.
The High-Risk HPV Strains Behind Most Cancers
Of the more than 200 known HPV types, 12 are classified as high-risk: HPV 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, and 59. Two of these, HPV 16 and HPV 18, are responsible for the majority of HPV-related cancers across all six sites. HPV 16 alone dominates in throat, anal, and cervical cancers.
These high-risk strains produce two proteins that essentially disable your body’s built-in brakes on cell growth. One protein blocks a tumor suppressor that normally triggers damaged cells to self-destruct. The other disables a protein that controls when cells divide. With both safety systems offline, infected cells can accumulate genetic damage and eventually become cancerous. This process is slow, typically unfolding over 10 to 20 years, which is why screening can catch precancerous changes long before they become dangerous.
Cervical Cancer
More than 9 out of every 10 cervical cancers are caused by HPV, making this the cancer most tightly linked to the virus. HPV 16 and 18 account for the largest share. Because cervical cancer develops gradually through detectable precancerous stages, routine screening is highly effective at catching it early.
Current screening guidelines recommend that people with a cervix begin testing at age 25 with an HPV test every five years, according to the American Cancer Society. An alternative is a combined HPV and Pap test every five years, or a Pap test alone every three years. Screening typically continues through age 65 for those with a history of normal results. People with HIV, weakened immune systems, or previous abnormal results may need more frequent testing.
Oropharyngeal Cancer
Cancers of the back of the throat, including the base of the tongue and tonsils, are now the most common HPV-related cancer among men. About 22,585 oropharyngeal cancers are diagnosed annually in the U.S., and roughly 70% of them (around 16,000 cases) are attributable to HPV. This cancer site has been rising sharply in recent decades even as smoking rates have declined, pointing to HPV as the primary driver of the trend.
Unlike cervical cancer, there is no established screening test for HPV-related throat cancer. Most cases are discovered when a person notices a persistent sore throat, difficulty swallowing, a lump in the neck, or ear pain on one side. The good news is that HPV-positive oropharyngeal cancers generally respond better to treatment and carry a more favorable prognosis than those caused by tobacco and alcohol use.
Anal and Rectal Cancer
HPV causes nearly all cases of anal cancer. The risk is elevated in people who have receptive anal sex, those with HIV, and anyone with a weakened immune system. Anal cancer is relatively uncommon in the general population, but rates have been climbing steadily over the past several decades in both men and women.
Symptoms can include bleeding, pain, itching, or a lump near the anus. Because these overlap with hemorrhoid symptoms, anal cancer is sometimes dismissed or diagnosed late. Some high-risk groups are now offered anal Pap tests (similar in concept to cervical screening) to detect precancerous changes, though this practice is not yet part of universal screening guidelines.
Penile Cancer
Penile cancer is rare, but HPV plays a role in a significant share of cases. HPV 16 is the most commonly detected strain. Risk factors beyond HPV include not being circumcised, smoking, and chronic inflammatory conditions of the foreskin. Symptoms typically involve a change in skin color, a thickening of the skin, or a growth on the penis that doesn’t heal. There is no routine screening test for penile cancer.
Vulvar and Vaginal Cancers
HPV is found in about 39% of vulvar cancers overall, with HPV 16 detected in roughly 78% of those HPV-positive cases. Vulvar cancer exists in two distinct forms: one is strongly linked to HPV and tends to affect younger women, while the other occurs independently of the virus and is more common in older women. Vaginal cancer is rarer still, but HPV is implicated in the majority of cases.
Symptoms of vulvar cancer include persistent itching, a visible lump or sore, or changes in skin color or texture on the vulva. Vaginal cancer may cause unusual bleeding, discharge, or a mass that can be felt during an exam. Neither cancer has a dedicated screening program, though abnormalities may be noticed during routine gynecological visits.
How Vaccination Is Reducing HPV Cancers
The HPV vaccine protects against the high-risk strains responsible for most of these cancers. Within 12 years of the vaccine’s introduction in the U.S., infections with the four HPV types it initially targeted dropped 88% among 14- to 19-year-old females and 81% among 20- to 24-year-old females. Cervical precancer rates among screened 18- to 20-year-olds fell by 50% compared to pre-vaccine years, and the proportion of cervical lesions caused by vaccine-targeted HPV types dropped 40% in vaccinated women.
The vaccine is most effective when given before any exposure to HPV, which is why it’s recommended starting at age 9 and routinely given at 11 or 12. It’s approved through age 45 for those who haven’t been vaccinated or haven’t completed the series. Because the vaccine prevents the infections that start the cancer process, its full impact on cancer rates will become clearer in the coming decades as vaccinated generations age into the years when HPV-related cancers typically appear.
Why Most HPV Infections Don’t Cause Cancer
HPV is extremely common. Most sexually active people will contract at least one type at some point in their lives. The vast majority of infections clear on their own within one to two years as the immune system eliminates the virus. Cancer only develops when a high-risk HPV infection persists for many years, giving the virus’s growth-disrupting proteins enough time to cause lasting genetic damage to cells. Factors that increase the chance of persistent infection include smoking, a weakened immune system, and having other sexually transmitted infections alongside HPV.