A World Health Organization (WHO) analysis estimates that infections contributed to about 12% of cancer cases worldwide in 2024--approximately 2.3 million new diagnoses. Published in The Lancet Oncology, the study highlights how preventing and treating certain infections could help reduce cancer rates.
Five pathogens accounted for most of the infection-related cases: Helicobacter pylori and human papillomavirus (HPV), each linked to about 4% of all cancers; hepatitis B, at 2%; Epstein-Barr virus, at 1%; and hepatitis C, at less than 1%. These infections are associated with several cancers, including cervical, stomach, liver and blood cancers.
How infections can contribute to cancer
Some viruses can interfere with the processes that normally control cell growth or remove damaged cells. Other infections, including bacterial and parasitic ones, may cause long-lasting inflammation and tissue damage. Over time, these effects can lead to genetic changes that raise the likelihood of cancer.
The findings point to practical ways to reduce risk. Vaccination against HPV and hepatitis B, screening, and timely treatment of infections such as hepatitis and H. pylori can all play a role. The study estimates that around three-quarters of infection-associated cancers occurred in low- and middle-income countries, underscoring the importance of making prevention and care widely accessible.
Expanding access to vaccines, screening and treatment could help prevent many infection-related cancers and strengthen cancer prevention worldwide.
