Infections Linked to One in Eight Cancers Worldwide, Study Finds

One in eight cancers globally, totaling approximately 2.3 million cases in 2024, are linked to infectious agents, according to a study published in The Lancet Oncology. Many of these infections can be prevented through vaccinations and other public health strategies, researchers from the International Agency for Research on Cancer have found.

The majority of infection-related cancers are attributed to five key infections: Helicobacter pylori (H. pylori), human papillomavirus (HPV), hepatitis B, hepatitis C, and Epstein-Barr virus (EBV). Low- and middle-income countries bear the largest burden, accounting for about 77 percent of these cases, with Eastern Asia seeing the highest number of infection-linked cancers due to H. pylori and hepatitis B.

The study underscores the importance of infection control in reducing cancer rates, with authors noting that while preventive vaccinations are key, cost-effective strategies are often underutilized due to societal, financial, and political barriers, particularly in regions that need them most.

Key Infections and Cancer Links

H. pylori, a common stomach bacterium, was identified as the leading infection-related cause of cancer worldwide, linked to an estimated 760,000 cases, primarily stomach cancers. Research also suggests H. pylori may be responsible for up to one in five bowel cancer cases, increasing the risk by 60 percent for those exposed. However, progress on developing H. pylori vaccines has been slow.

HPV, a virus transmitted through close skin-to-skin contact, is linked to nearly all cervical cancer cases and also contributes to cancers of the throat, mouth, anus, penis, vulva, and vagina. In Western Europe, HPV was the biggest infection-related cause of cancer in 2024, associated with 24,000 cases. HPV vaccination and cervical screening are central to global strategies aimed at eliminating cervical cancer.

Combined, hepatitis B and C accounted for approximately one-third of infection-related cancers, most commonly liver cancer. These cancers are considered highly preventable due to the existence of effective treatments and vaccines for hepatitis B. Hepatitis C can be cured in most patients, and prevention relies on testing, treatment, and reducing exposure. The NHS in the UK recommends hepatitis B vaccination for infants and high-risk individuals.

Epstein-Barr virus (EBV), which infects a vast majority of adults, is now considered the fourth-largest global cause of cancer, ahead of hepatitis C. Researchers noted this is concerning given the virus's prevalence, and while infection alone is unlikely to cause cancer, EBV is considered an important target for prevention, with clinical trials for EBV vaccines underway.

Prevention Strategies and Barriers

Preventive measures recommended include increasing HPV vaccine uptake, promoting safe injection practices, expanding access to condoms and HIV prevention drugs, and early detection and treatment of cervical and anal cancers. For H. pylori, some European countries are screening for the bacterium, but vaccine development remains a challenge.

Researchers highlighted that strategies such as vaccination are cost-effective but often face underutilization due to societal, financial, and political obstacles, particularly in the regions most affected. The findings emerge amid concerns about rising rates of early-onset cancers, especially in women, and as governments consider national plans to improve lifestyles, diagnosis, and treatment.