HPV infection is the primary cause of cervical cancer

Nearly all cervical cancers start with a persistent infection from human papillomavirus, or HPV. HPV is a common virus spread through sexual contact. Most people who get HPV clear it on their own within a year or two, but in some people the infection persists and can eventually damage the cells of the cervix—the lower part of the uterus that connects to the vagina.

There are more than 200 types of HPV. Only a handful cause cancer, and the two most dangerous are HPV-16 and HPV-18. These high-risk types are responsible for about 70 percent of all cervical cancers. The virus works slowly: it typically takes 10 to 20 years from the time of infection for cancer to develop, which is why cervical cancer is largely preventable with screening and vaccination.

Key Takeaways

  • HPV infection causes nearly all cervical cancers, but most HPV infections clear on their own without causing harm.
  • Only high-risk types of HPV—mainly HPV-16 and HPV-18—can lead to cancer, and this usually takes 10 to 20 years.
  • Smoking, a weakened immune system, and long-term use of birth control pills increase the risk that an HPV infection will persist and become cancerous.
  • Regular Pap tests or HPV tests can catch precancerous changes before they become cancer, making prevention possible.
  • The HPV vaccine prevents infection with the high-risk types and is most effective when given before sexual activity begins.

How HPV spreads and why most infections don't cause cancer

HPV spreads through skin-to-skin contact during sexual activity. A person can have HPV without knowing it, because the virus often causes no symptoms. Most people who contract HPV—roughly 90 percent—will clear the infection naturally within two years as their immune system fights it off.

The problem occurs when the immune system does not clear the virus. In these cases, the HPV stays in the cells of the cervix and can cause changes over time. These changes start as precancerous lesions, which are abnormal cell growths that are not yet cancer but can become cancer if left untreated. This is why the time between infection and cancer is so long: the virus has to persist, then gradually damage the cells, then those cells have to become truly cancerous.

Factors that increase the risk of persistent HPV infection

Certain conditions make it more likely that an HPV infection will stick around and lead to cancer. A weakened immune system—from HIV, organ transplant medications, or other causes—is one of the strongest risk factors. People with HIV who do not take antiretroviral therapy have a much higher risk of cervical cancer because their immune system cannot fight off the persistent HPV infection.

Smoking also increases risk. Tobacco smoke damages immune cells in the cervix and makes it harder for the body to clear HPV. People who smoke are two to three times more likely to develop cervical cancer than non-smokers with the same HPV infection.

Long-term use of hormonal birth control pills for five years or more is associated with increased cervical cancer risk, though the exact reason is not fully understood. The risk appears to decrease after stopping the pills. Having many sexual partners or having a partner with multiple partners increases the chance of exposure to high-risk HPV types. Early sexual activity—before age 18—also raises risk, possibly because the cervix is still developing and more vulnerable to HPV damage.

Other factors that contribute to cervical cancer risk

Pregnancy and childbirth may play a role. Some research suggests that pregnancy hormones or the physical stress of childbirth can affect how the immune system handles HPV, though this is still being studied. Having many pregnancies is associated with higher cervical cancer risk.

Chlamydia infection, a sexually transmitted bacterial infection, has been linked to cervical cancer risk in some studies, though it is not clear whether chlamydia itself causes cancer or whether it is a marker for other risk factors. Diethylstilbestrol (DES) exposure in the womb—which occurred to daughters of women who took this synthetic hormone in the 1950s and 1960s—increases cervical cancer risk, though this is now a historical concern.

Family history of cervical cancer may indicate shared risk factors or genetic differences in how the immune system responds to HPV, but cervical cancer itself is not inherited.

How screening and vaccination prevent cervical cancer

Because cervical cancer develops slowly from precancerous changes, regular screening can catch and treat these changes before cancer develops. A Pap test looks for abnormal cells on the cervix. An HPV test detects the virus itself. Both can identify problems years before cancer would appear, making treatment simple and highly effective.

The HPV vaccine prevents infection with the high-risk types of HPV that cause most cervical cancers. It is most effective when given before a person becomes sexually active, but it can still provide protection if given later. The vaccine does not treat an existing HPV infection, but it prevents future infections with the types it covers.

What happens after HPV infection is detected

If an HPV test comes back positive, it does not mean cancer will develop. Most people will clear the infection. Your doctor will likely recommend follow-up testing to see whether the infection persists and whether any cell changes have occurred. If precancerous changes are found, they can be removed with procedures like colposcopy with biopsy or loop electrosurgical excision procedure (LEEP), which have high success rates.

Regular follow-up screening after treatment is important to make sure the changes do not return. The key is catching changes early, before they become cancer.

Frequently Asked Questions

Can you get cervical cancer without HPV?

Rarely. HPV causes about 99 percent of cervical cancers. The small remaining percentage may be related to other factors or may have been caused by HPV that was not detected, but HPV is the overwhelming cause.

If I have HPV, will I definitely get cervical cancer?

No. Most people who get HPV clear it on their own. Only a small percentage of people with persistent high-risk HPV infection develop cancer, and that usually takes 10 to 20 years. Regular screening can catch precancerous changes before they become cancer.

Can men get cervical cancer?

No, because men do not have a cervix. However, men can carry HPV and pass it to sexual partners. HPV can cause other cancers in men, including throat and anal cancers, though these are less common.

Is cervical cancer hereditary?

Cervical cancer itself is not inherited, but some people may have genetic differences that affect how their immune system responds to HPV. Family history of cervical cancer may indicate shared risk factors rather than a genetic predisposition.

Can I reduce my risk of cervical cancer if I already have HPV?

Yes. Quitting smoking, maintaining a healthy immune system, and attending all recommended screening appointments are important. The HPV vaccine may still provide some protection against other high-risk types you have not yet encountered.