HPV causes cancer when a sexually transmitted infection that would normally clear on its own instead persists for years or decades, giving the virus time to damage cells and trigger uncontrolled growth. About 80% of HPV infections resolve without treatment, but the 10 to 20% that linger can slowly transform healthy tissue into precancerous and eventually cancerous cells. In the United States, HPV is responsible for an estimated 39,300 cancers each year.
How HPV Spreads
HPV is transmitted through sexual contact, including vaginal, anal, and oral sex. It also spreads through close skin-to-skin touching during sex, which means penetrative intercourse isn’t the only route. Condoms reduce the risk but don’t eliminate it, because the virus can live on skin that a condom doesn’t cover. HPV is extremely common: most sexually active people will be exposed to it at some point in their lives.
You can carry HPV without knowing it. The virus often produces no symptoms and can remain dormant for years before causing any changes. That long silent period is part of why HPV-related cancers can feel like they come out of nowhere.
What the Virus Does Inside Your Cells
Not all HPV strains are dangerous. There are over 200 types, and only a subset are classified as high-risk. The ones most strongly linked to cancer produce two proteins that essentially disable your cells’ built-in safety systems.
The first protein targets p53, a molecule your cells rely on to detect DNA damage and either repair it or trigger cell death. The virus hijacks a cellular process called ubiquitination to break down p53, removing this critical checkpoint. The second protein goes after a different safeguard called pRb, which normally prevents cells from dividing too quickly. When this protein is knocked out, cells are forced into premature division, copying themselves before they’re ready. With both brakes removed, damaged cells multiply unchecked, and over time that uncontrolled growth can become cancer.
Why Most Infections Never Become Cancer
Your immune system clears the majority of HPV infections within one to two years. Only 10 to 20% of infections persist in a latent state, and even among those, only a fraction progress to cancer. The progression is slow: it typically takes 5 to 10 years for HPV-infected cervical cells to develop into precancers, and roughly 20 years from initial infection to invasive cancer. That long timeline is actually good news, because it creates a wide window for screening to catch problems early.
Several factors make it more likely that an infection will persist and progress rather than clear:
- Weakened immune system. People living with HIV, taking immunosuppressive medications after an organ transplant, or being treated for autoimmune diseases are less able to fight off the virus. HPV infections in immunocompromised people are more likely to become persistent and eventually cancerous.
- Smoking and secondhand smoke. Tobacco exposure increases the risk of cervical cancer specifically, and the risk rises the more a person smokes or is exposed.
- Multiple or prolonged exposures. Repeated exposure to high-risk HPV strains gives the virus more opportunities to establish a persistent infection.
Which Cancers HPV Causes
HPV is most closely associated with cervical cancer, where it’s responsible for about 91% of cases, roughly 11,100 diagnoses per year in the U.S. But cervical cancer is far from the only one. The virus causes cancers in six areas of the body: the cervix, vagina, vulva, penis, anus, and oropharynx (the back of the throat, including the base of the tongue and tonsils).
Throat cancer is now the largest category by sheer numbers. About 16,000 oropharyngeal cancers per year are attributed to HPV, with men accounting for the vast majority: roughly 13,600 of those cases. Anal cancer follows, with about 7,600 HPV-caused cases annually. Penile cancer is less common, at around 900 cases per year, but 63% of those are linked to the virus.
Overall, men develop about 16,800 HPV-attributable cancers each year in the U.S., compared to 22,500 in women. The gap is narrower than many people expect, largely because of the rising rates of HPV-driven throat cancer in men.
How Screening Catches It Early
For cervical cancer, routine screening is the most effective way to detect problems long before they become cancer. Current guidelines from the U.S. Preventive Services Task Force recommend Pap tests every three years for women aged 21 to 29. Starting at age 30, you have three options: a Pap test every three years, an HPV test every five years, or both tests together every five years. Screening more often than these intervals doesn’t meaningfully improve outcomes and increases the chance of unnecessary procedures for abnormalities that would have resolved on their own.
For other HPV-related cancers, screening is more limited. There is no routine screening test for throat, anal, or penile cancers in the general population, which makes prevention through vaccination especially important. Some higher-risk groups, such as men who have sex with men and people living with HIV, may be offered anal cancer screening, but this isn’t yet a universal recommendation.
How Vaccination Prevents HPV Cancer
The HPV vaccine is the most direct way to prevent these cancers. A large Swedish study of nearly 1.7 million women found that girls vaccinated before age 17 had a nearly 90% reduction in cervical cancer incidence over an 11-year period compared to unvaccinated women. Even when including women vaccinated at older ages, the overall reduction was 63%.
The vaccine works best when given before any exposure to the virus, which is why it’s recommended starting at age 11 or 12. It’s approved for people up to age 26, and in some cases up to 45 for those who haven’t been previously vaccinated. The vaccine targets the high-risk HPV strains most likely to cause cancer, and its protection has held up over more than a decade of follow-up data. It does not treat existing infections, so it can’t reverse an HPV infection you already have, but it can still protect against strains you haven’t yet encountered.