Common Infections Are Driving Millions of Cancer Cases — And Most Are Preventable

A Startling Link Between Everyday Infections and Cancer

Millions of new cancer cases around the world may be caused by infections that are either treatable or preventable — meaning the cancer could have been avoided altogether. That's according to new research published in The Lancet Oncology, which found that roughly 1 in 8 cancer cases around the world may be linked to infections, many of which can be prevented through vaccines, screening, or relatively straightforward treatments.

Harriet Rumgay, PhD, of the World Health Organization's International Agency for Research on Cancer, and colleagues used data from the Global Cancer Observatory's Cancer Today database to estimate the number, proportion, and incidence of cancers attributable to 12 infections classified as carcinogenic. The study found that an estimated 2.3 million new cancer cases were attributable to infections globally in 2024, equivalent to 12% of all cancer cases.

The Biggest Culprits

Two infections stood out in particular: Helicobacter pylori, commonly known as H. pylori — mostly associated with gastric cancers — and human papillomavirus, or HPV, predominantly associated with cervical cancer. Together, researchers estimate that these two infections accounted for more than 1.5 million cancer cases in 2024.

HPV was linked to about 750,000 cancer cases globally, which were predominantly cervical cancer, as well as anal, vulvar, vaginal, and penile cancers and some head and neck cancers. HBV was linked to about 360,000 cancer cases in 2024, and most were cases of liver cancer. EBV was linked to about 260,000 cancer cases globally, which were largely nasopharyngeal cancer, some gastric cancers, and Hodgkin lymphoma. HCV was linked to about 160,000 cancer cases, most of which were liver cancer.

H. pylori, which is transmitted via saliva and contaminated food or water, is more common in lower-income countries, and most people are infected during childhood. It can be treated with antibiotics and medications that reduce stomach acid. Epstein-Barr virus (EBV) is a common herpesvirus that causes mononucleosis, persists in the body, and can trigger nasopharyngeal cancer, certain types of lymphoma, and stomach cancer.

A Burden Falling Hardest on the Poorest Nations

The new study also highlights that around 75% of cancers caused by infections were found in low- and middle-income countries. The largest burden of infection-attributable cancer was in eastern Asia, with 990,000 cases — 42% of the global total. Rates were also higher than the global average in sub-Saharan Africa, central and eastern Europe, and southeastern Asia.

Despite progress in vaccination and screening, infection-related cancers remain a major challenge globally, with persistent inequities especially impacting low-income and middle-income countries. While many effective prevention tools for these infections already exist — including vaccination against HPV and HBV, and testing and treatment for infections such as H. pylori, HBV, HCV, and HIV — these interventions are often underused or inaccessible.

The Case for Prevention

"This recent Lancet data is a profound reminder that a significant portion of our global cancer burden is fundamentally preventable," said David Greenberg, MD, of Hackensack Meridian Jersey Shore University Medical Center. Treating infections that can lead to cancer — such as HIV, H. pylori, and hepatitis B and C — is one way to reduce cancer rates, while preventive measures also play a major role, including vaccinations, condoms, and disease screening.

Researchers say there is a need to "expand vaccination and make testing and treatment of persistent infections more accessible," as well as strengthen cancer screening in high-risk populations and improve access in low- and middle-income countries where most of the infection-related cancer burden occurs. With global cancer diagnoses projected to rise sharply in the coming decades, infectious agents are already estimated to be the leading modifiable risk factor for cancer among women in 141 countries and men in 58 countries — making this not just a medical story, but a global public health imperative.