One in eight cancers starts with an infection. Most of them don't have to.

When we think about preventing cancer, most of us think about the usual suspects: tobacco, diet, physical activity, and sun exposure. Those matter a lot. But there is another side of cancer prevention that gets far less attention, and it may be one of the most hopeful stories in public health.

A new study from the World Health Organization's cancer research agency found that about 1 in 8 new cancers worldwide, roughly 2.3 million cases a year, are caused by infections. Many of those cancers can be prevented with tools we already have: vaccines, screening tests, and treatment.

Five infections, millions of cancers

H. pylori, a common stomach bacterium, is linked to about 760,000 cancer cases a year, mostly stomach cancer. Many people carry it for years without knowing. Human papillomavirus (HPV) is linked to about 750,000 cases, including nearly all cervical cancers and some throat and other cancers. Hepatitis B is linked to about 360,000 cases, mostly liver cancer. Epstein-Barr virus, best known for causing mono, is linked to about 260,000 cases, including some lymphomas. Hepatitis C is linked to about 160,000 cases, mostly liver cancer.

Most of these cases happen in low- and middle-income countries. But the United States has its own gaps, and they fall hardest on the same communities that struggle to get care of any kind.

What prevention looks like here at home

HPV vaccination. CDC estimates that about 92% of cancers caused by HPV could be prevented by the vaccine. Yet CDC's latest national survey found that only 63.4% of U.S. teens are fully up to date, and that number has not improved since 2021. Teens in mostly rural areas are 12 percentage points less likely to have gotten even one dose than teens in cities, and that gap holds across income levels.

Hepatitis C testing and cure. More than 2.4 million Americans have hepatitis C, and the true number may be closer to 4 million. About one-third do not know they have it. That matters, because hepatitis C can now be cured in more than 95% of cases, usually with 8 to 12 weeks of pills. CDC recommends that every adult be tested at least once. A cure only helps people who know they need one.

Hepatitis B vaccination. This is one of the first cancer-prevention vaccines. It is recommended for babies at birth and for adults who missed it.

H. pylori testing and treatment. For people with ongoing stomach trouble or a family history of stomach cancer, testing and treating H. pylori is linked to a 36% lower rate of stomach cancer.

What I learned in Tanzania

I have seen what infection-related cancer prevention looks like up close. In Tanzania, one of the African countries with the highest rates of cervical cancer, I worked with partners including The Aga Khan Hospital to advance HPV prevention, supporting education, screening, and early-intervention strategies to reduce women's risk.

That experience reinforced a lesson I have carried throughout my career. The science is only the starting point. Vaccines and screening tests save lives only when communities trust them, understand them, and can actually reach them. The progress we made came from building local capacity, training providers, and meeting women where they live, not from top-down campaigns.

Cervical cancer is more than 90% preventable, according to WHO. Whether a woman gets it often depends less on biology than on geography and access.

Prevention is a matter of equity

This is true around the world, and it is true in rural Georgia, the Mississippi Delta, and Appalachia. When a teen in a rural county is less likely to be vaccinated than a teen in the suburbs, or an adult never gets tested for hepatitis C because the nearest clinic is an hour away, that is not a personal failing. It is a gap in our systems.

Global vaccination efforts have saved millions of lives because they are built on a simple idea: everyone, no matter where they live, deserves access to proven protection. The same idea should guide prevention here at home.

What you can do

Check your family's vaccine records. HPV vaccination is recommended at ages 11 to 12, and for everyone through age 26 who was not vaccinated earlier. Adults 27 to 45 can talk with their doctor. Get tested for hepatitis C at least once as an adult, even if you feel fine. Make sure you are protected against hepatitis B. Do not ignore ongoing stomach problems; ask your doctor whether H. pylori testing makes sense. And keep up with recommended cancer screenings, including cervical cancer screening.

The bigger picture

At ProVention Health Foundation, our work focuses on preventing chronic disease before it starts, through healthy habits, early action, and programs that reach people where they live. Infection-related cancers remind us that prevention comes in many forms. Sometimes it is a daily walk or a better meal. Sometimes it is a plan to quit tobacco, still one of the leading causes of cancer. And sometimes it is a single vaccine or a simple blood test.

We already have some of the most powerful cancer-prevention tools in medicine. The work now is making sure everyone can use them.

Sources: International Agency for Research on Cancer analysis (reported by Gavi, September 2026); CDC, Vaccination Coverage Among Adolescents, National Immunization Survey-Teen 2025 (MMWR, 2026); CDC, Hepatitis C Prevention and Control; CDC, HPV vaccine cancer prevention estimates; World Health Organization Africa Region.