Infections Drive One in Eight Cancers Globally, Study Finds

Infections are responsible for one in eight cancer cases globally, according to a new study by the International Agency for Research on Cancer. Researchers found that out of approximately 19.2 million new cancer cases in 2024, around 2.3 million were attributable to infections, many of which could be prevented through vaccinations and other public health measures.

The vast majority of these infection-related cancers are linked to five key infections: Helicobacter pylori (H. pylori), human papillomavirus (HPV), hepatitis B and C, and the Epstein-Barr virus (EBV). Low- and middle-income countries bear the heaviest burden, accounting for roughly 77 percent of all infection-related cancer cases. Eastern Asia alone accounts for 42 percent of the global total, primarily driven by H. pylori and hepatitis B.

The study, published in The Lancet Oncology, emphasizes the critical role of infection control in reducing cancer incidence. Authors noted that while investment in preventive vaccines is crucial, many cost-effective prevention strategies remain underutilized due to societal, financial, and political barriers, particularly in regions where they are most needed.

Effective strategies include increasing HPV vaccination rates, promoting safe injection practices, enhancing access to condoms and pre-exposure prophylaxis (PrEP) for HIV prevention, and early detection and treatment of cervical and anal cancers. In Western Europe, HPV was the leading infection-related cause of cancer in 2024, linked to 24,000 cases. HPV, a common virus spread through skin-to-skin contact, is responsible for nearly all cervical cancer cases and is also associated with cancers of the throat, mouth, anus, penis, vulva, and vagina. The World Health Organization's strategy to eliminate cervical cancer centers on HPV vaccination and screening.

H. pylori, a bacterium that infects the stomach, was identified as the single largest infection-related cause of cancer worldwide in 2024, contributing to approximately 760,000 cases, primarily stomach cancers. Emerging research also suggests H. pylori may be linked to up to one in five bowel cancer cases. However, progress on developing vaccines against H. pylori has been slow.

Epstein-Barr virus (EBV), which infects a vast majority of the global adult population, is now the fourth-largest cause of cancer globally, surpassing hepatitis C. The study authors noted this finding is concerning due to the virus's prevalence, although they stressed that infection alone is rarely the sole cause of cancer, with genetics, overall health, and diet also playing significant roles.

Hepatitis B and C combined were linked to about a third of all infection-related cancers, predominantly liver cancer. These cancers are considered highly preventable, as effective treatments are available. Hepatitis B can be managed with antiviral drugs, and hepatitis C can be cured in most patients. While a hepatitis B vaccine is part of routine childhood immunizations in some regions, there is no approved vaccine for hepatitis C, with prevention relying on testing, treatment, and reducing exposure.