Infections Linked to 1 in 8 Cancer Cases, Lancet Study Finds

One in eight cancer cases diagnosed worldwide in 2024 was linked to an infection, according to a landmark global analysis published in The Lancet Oncology. The study, led by researchers at the International Agency for Research on Cancer (IARC), estimates that infections were behind about 2.3 million new cancer cases globally last year — the most detailed accounting yet of how infections fuel the global cancer burden.

Microscopic view of H. pylori bacteria driving gastritis in stomach tissue. H. pylori was linked to around 760,000 cancer cases in 2024 — the largest share in the IARC study. Credit: Fung C, Tan S, Nakajima M, Skoog EC, Camarillo-Guerrero LF, Klein JA, et al. (CC BY 4.0)

2.3 Million Cases: Five Infections Drive Nearly All Cases

The IARC team analysed worldwide cancer data from its Global Cancer Observatory across 12 infectious agents known to cause cancer — including H. pylori, HPV, hepatitis B and C, Epstein-Barr virus, HIV, and others. Just five infections accounted for almost all infection-related cases:

• H. pylori — around 760,000 cases, mainly stomach cancer; the largest contributor
• HPV (human papillomavirus) — about 750,000 cases, the main cause of cervical cancer plus several other cancers
• Hepatitis B virus — roughly 360,000 cases, primarily liver cancer
• Epstein-Barr virus (EBV) — around 260,000 cases, including nasopharyngeal cancers, some stomach cancers and lymphomas
• Hepatitis C virus — about 160,000 cases, mostly liver cancer

The study also folds in newly recognised infection-cancer links, such as the recent evidence connecting EBV with gastric cancer.

The Burden Falls Hardest on Poorer Countries

Infection-related cancers are not spread evenly. Low- and middle-income countries accounted for about 77% of infection-related cancers, driven by differences in infection prevalence and access to vaccination, screening, testing and treatment.

The researchers stress that infection does not mean cancer is inevitable. Risk depends on whether an infection persists, how the immune system responds, and other individual factors — chronic infections can cause inflammation or cellular damage that contributes to cancer over years.

Vaccines and Screening Can Prevent Many of These Cancers

Perhaps the most actionable finding: several of these cancers are preventable with tools that already exist. HPV and hepatitis B vaccination can lower cancer risk, cervical screening can catch precancerous changes early, and while there is no hepatitis C vaccine, antiviral medicines can cure most infections.

How HPV vaccination reduces precancerous cervical lesions — HPV is linked to around 750,000 cancer cases a year, mostly cervical cancer, and is one of the infection-related cancers preventable by vaccine. Credit: Centers for Disease Control and Prevention (CC0)

The findings highlight infection prevention, early detection and treatment as important components of global cancer prevention.

The takeaway: roughly 12% of all new cancers in 2024 trace back to infections — and a meaningful share of those are avoidable. Expanding vaccination, screening and antiviral treatment, especially in the countries carrying the heaviest burden, could prevent hundreds of thousands of cancers a year.

🎥 Watch: Can Infections Cause Cancer? — Medical Dialogues video explainer on the Lancet study

Sources

• Rumgay H, Georges D, Huang Y et al.; "Global burden of cancer attributable to infections in 2024: a worldwide incidence analysis"; The Lancet Oncology; DOI: 10.1016/S1470-2045(26)00307-4
• Medical Dialogues: "Can Infections Cause Cancer? Lancet Study Links 1 in 8 Cancer Cases to Infections"
• KTOK/iHeart: "One In Eight Global Cancer Cases In 2024 Linked To Infections" (IARC analysis summary)