HPV (human papillomavirus) is the cause of virtually all cervical cancer. About 91% of cervical cancers in the United States are caused by HPV infection, accounting for roughly 11,100 cases per year. But having HPV doesn’t mean you’ll get cancer. The vast majority of HPV infections clear on their own and never cause any problems.
How HPV Leads to Cervical Cancer
There are over 200 types of HPV, but only about 14 are classified as high-risk for cancer. Two strains do most of the damage: HPV type 16 causes approximately 50% of cervical cancers worldwide, and types 16 and 18 together account for about 66%.
When a high-risk HPV infection doesn’t clear, the virus produces proteins that interfere with your body’s built-in cancer defenses. One protein disables p53, a molecule your cells rely on to stop damaged cells from multiplying. Another protein overrides a second safety mechanism (called Rb) that normally keeps cell division in check. With both brakes disabled, infected cervical cells can grow uncontrollably, accumulating genetic damage over time.
This process is slow. Cancer usually takes years, even decades, to develop after an HPV infection. The virus first causes abnormal cell changes (precancerous lesions) that can be caught on screening long before they become invasive cancer.
Most HPV Infections Never Become Cancer
Between 80% and 90% of HPV infections are transient, meaning your immune system clears the virus within about two years. Most people who get HPV will never know they had it because the infection causes no symptoms at all. It’s only the small fraction of infections that persist for years that carry a real cancer risk. Even among those persistent infections, not all progress to precancer or cancer.
Symptoms to Watch For
HPV itself is silent. There are no symptoms during the initial infection, which is why screening matters so much. Cervical cancer also causes no symptoms in its earliest stages. By the time symptoms appear, the cancer has typically been growing for some time.
Symptoms that can signal cervical cancer include:
- Vaginal bleeding that’s unusual for you, such as bleeding after sex or between periods
- Watery vaginal discharge with a strong odor or blood in it
- Pelvic pain or pain during sex
If the cancer has spread, additional signs can include painful urination, blood in the urine, rectal bleeding, a persistent dull backache, swollen legs, or unusual fatigue. None of these symptoms are unique to cervical cancer, but any of them warrants a medical evaluation.
How Screening Catches It Early
Because HPV and early cervical cancer produce no symptoms, routine screening is the main way precancerous changes get found and treated before they progress. Updated guidelines from the American College of Obstetricians and Gynecologists recommend the following for people at average risk:
- Ages 21 to 29: Screening with cervical cytology (a Pap test) as previously recommended.
- Ages 30 to 65: Primary HPV testing every five years is now the preferred approach. Self-collected HPV testing every three years is also an option for this age group.
The HPV test looks directly for the virus’s DNA in cervical cells, making it more sensitive than a Pap test alone at catching infections that could lead to cancer. If an HPV test comes back positive for a high-risk strain, your provider will determine whether you need closer monitoring or a procedure to examine the cervix more closely.
How the HPV Vaccine Changes the Picture
The HPV vaccine targets the high-risk strains most likely to cause cancer, and the real-world results have been striking. In the U.S., cervical precancer rates among screened 18- to 20-year-olds dropped by 50% between 2008 and 2015, and by 36% in 21- to 24-year-olds over the same period. The percentage of cervical lesions caused by HPV types covered by the vaccine dropped 40% in vaccinated women.
Population-level data from Sweden and Denmark show that women vaccinated in their teens have a lower risk of cervical cancer as adults. The vaccine is recommended for preteens starting at age 11 or 12, though it can be given as early as 9 and provides the most benefit when given before any exposure to HPV. Catch-up vaccination is available through age 26, and in some cases up to age 45 after a conversation with a healthcare provider.
The vaccine doesn’t treat existing infections or precancerous changes. It prevents new infections from the strains it covers. Even vaccinated individuals still benefit from routine cervical screening, since the vaccine doesn’t protect against every high-risk HPV type.
Why HPV Is Common but Cervical Cancer Is Not
HPV is the most common sexually transmitted infection in the United States. Most sexually active people will get at least one type of HPV at some point. Yet cervical cancer is relatively uncommon, with about 12,300 cases diagnosed each year. The gap between HPV’s prevalence and cervical cancer’s rarity comes down to three layers of protection: the immune system clears most infections naturally, screening catches precancerous changes before they progress, and vaccination prevents the most dangerous infections from happening in the first place. When all three are working together, cervical cancer is one of the most preventable cancers there is.