1 in 8 cancer cases worldwide are caused by infections, study finds

Researchers at the International Agency for Research on Cancer estimate infections caused 2.3 million new cancer cases in 2024, about 12% of all newly diagnosed cancers. The largest single attributable burden was Helicobacter pylori (≈760,000 cases), mainly stomach cancer in eastern Asia, followed by human papillomavirus (≈750,000 cases), which causes all cervical cancers and many anal, genital and some head-and-neck cancers, with high rates in sub-Saharan Africa. Hepatitis B and C viruses accounted for a substantial share of liver cancers, and Epstein-Barr virus was newly recognized as linked to roughly 260,000 cases (nasopharyngeal, some gastric cancers and Hodgkin lymphoma). The analysis expanded the list of infection-associated cancers by 16 entities, including links involving HIV and Merkel cell polyomavirus, using attributable-fraction calculations applied to global cancer registries.

The report highlights large regional disparities tied to historical access to vaccination, screening and treatment; high-income countries show lower infection-attributable burdens. In Canada, prior work estimated infections cause about 4% of cancers (≈7,000 cases/year), with HPV and H. pylori prominent. Authors call for scaling proven prevention measures - higher HPV vaccination and screening coverage, targeted H. pylori detection and treatment for high-risk populations - and for intensified research and preventive strategies against Epstein-Barr virus, which currently lacks vaccine or effective control tools.