Cervical Cancer Risk Factors

Cervical cancer is unusual. Doctors know almost exactly what causes it: long-lasting infection with certain types of HPV, the human papillomavirus. That is also why it is one of the most preventable cancers. Vaccination and regular screening both help.

HPV is a very common virus. It spreads mainly through sexual contact. Most people who get it clear the infection on their own within one to two years. Many never know they had it. Trouble starts when a high-risk type lingers instead of clearing. Over years, a lasting infection can change cervical cells. Some of those changes eventually become cancer. Two HPV types, called 16 and 18, cause about 70% of cervical cancers worldwide.

Long-lasting infection with high-risk HPV causes almost all cervical cancer.

A weakened immune system makes it harder to clear HPV. That means infection is more likely to stick around. This includes:

• people living with HIV
• people who have had an organ transplant
• people taking medicines that suppress the immune system

Smoking raises risk too. This is true whether you smoke directly or breathe secondhand smoke often. Chemicals from tobacco seem to weaken the immune system's fight against HPV in the cervix. More smoking is linked to more risk.

A few other things raise risk, though scientists do not fully know why. These include:

• long-term use of birth control pills
• having many full-term pregnancies
• obesity
• starting sexual activity at a young age

None of these causes cervical cancer alone. They seem to add risk mainly by affecting whether HPV persists or causes lasting change.

Skipping regular screening is its own risk factor. It does not raise your chance of getting HPV. It raises the chance that a change on the cervix goes unnoticed until it becomes cancer.

The HPV vaccine, brand name Gardasil 9, prevents infection with nine HPV types. Seven of them are high-risk types that cause most cervical cancers, and the other two cause most genital warts. The CDC recommends routine vaccination at ages 11 to 12, and for everyone through age 26 who is not yet vaccinated. The FDA has approved it up to age 45. For ages 27 to 45 the CDC does not recommend it routinely, so it is a choice to make with your doctor.

The vaccine does not protect against every cancer-causing HPV type. That is why regular screening still matters, usually starting in your 20s. A Pap test looks for abnormal cervical cells. An HPV test looks for the virus itself. Together, they catch problems years before cancer could develop. Condoms lower the chance of spreading HPV during sex. They do not fully prevent it, since HPV can infect skin a condom does not cover.

The CDC recommends starting Pap tests at age 21. From 21 to 29, a Pap test every three years is standard if results stay normal. From 30 to 65, you have three options:

• an HPV test alone every five years
• an HPV and Pap test together every five years
• a Pap test alone every three years

After 65, some people can stop screening. The CDC says this applies if you have had at least three normal Pap tests or two normal HPV tests in the past 10 years and no history of precancer. Ask your doctor which schedule fits you.

Ask whether you are up to date on cervical screening. Ask how often you need it. Ask whether you or your children should get the HPV vaccine, and when. Ask whether anything in your health history raises your risk. Ask what an abnormal result would mean for next steps.

• National Cancer Institute — Cervical Cancer Causes, Risk Factors, and Prevention
• CDC — Cervical Cancer Screening
• National Cancer Institute — Human Papillomavirus (HPV) Vaccines