Infections are responsible for a far larger share of the global cancer burden than many people realize, according to a new analysis published in The Lancet Oncology. Researchers estimate that in 2024, around 2.3 million newly diagnosed cancer cases worldwide, or 12 percent, were linked to infectious agents.
The study identifies just five pathogens as the main drivers behind almost all infection-related cancers: Helicobacter pylori, human papillomavirus, hepatitis B virus, Epstein-Barr virus and hepatitis C virus. Together, they account for millions of potentially preventable cancer cases.
Five pathogens behind most cases
Helicobacter pylori, a bacterium that colonizes the stomach lining, was associated with about 4 percent of all cancers diagnosed in 2024, or roughly 760,000 cases. It is one of the most widespread infections worldwide, with an estimated one in two people carrying the bacterium.
Most H. pylori infections cause no obvious symptoms, but some strains can trigger chronic inflammation, ulcers and eventually stomach cancer. The authors note that progress toward vaccines or highly effective treatments that minimize antibiotic resistance has been slow, leaving a major gap in global cancer prevention.
Human papillomavirus was also linked to 4 percent of cancers, representing about 750,000 new cases, including cervical, anal, and head and neck cancers. Hepatitis B virus accounted for around 2 percent of new cancers, primarily liver cancer, while Epstein-Barr virus contributed approximately 1 percent. Hepatitis C virus was linked to less than 1 percent of cases.
Epstein-Barr virus, which infects about 95 percent of adults worldwide, is a relatively new addition to estimates of the global cancer burden. Growing evidence links EBV to several malignancies, including certain lymphomas and nasopharyngeal cancer, prompting researchers to include it as a major carcinogenic pathogen.
Unequal impact across the globe
The burden of infection-related cancers is not distributed evenly. According to the study, roughly three-quarters of these cases occur in low-income and middle-income countries, where access to vaccination, screening and treatment is often limited.
Eastern Asia alone accounted for about 42 percent of all infection-linked cancer diagnoses in 2024. In this region, H. pylori and hepatitis B play a dominant role, reflecting both high infection prevalence and gaps in long-term disease control.
Sub-Saharan Africa and parts of southeastern Asia also carry a disproportionate share of cases. Researchers highlight that these regions often face overlapping challenges, including limited healthcare infrastructure, high rates of chronic infection and financial barriers to preventive care.
Prevention tools and missed chances
The findings underscore that many infection-related cancers are theoretically preventable using tools that already exist. Vaccines against HPV and hepatitis B, early diagnostics, antiviral therapies and safe injection practices can substantially reduce cancer risk when widely implemented.
However, implementation remains uneven. HPV vaccination programs often focus primarily on adolescent girls, leaving boys and men underprotected despite their risk of HPV-related cancers. Coverage of hepatitis B vaccination and testing also varies considerably between and within countries.
By contrast, there are currently no licensed vaccines to prevent EBV infection and no widely adopted vaccine for H. pylori. Several vaccine candidates targeting EBV and H. pylori are in clinical development, but experts caution that even successful products would require sustained funding and political commitment to reach populations at greatest risk.
The authors argue that existing strategies, including expanding HPV and hepatitis B immunization and improving access to cancer screening, are already known to be cost-effective. Yet they remain underused because of social stigma, financial constraints and political barriers, particularly in settings where healthcare systems are already under strain.
Call for investment in prevention
Lead author Harriet Rumgay and colleagues emphasize that infection control should become a central pillar of global cancer prevention strategies. They call for stronger investment in vaccines, improved diagnostics and wider access to antiviral treatments in both wealthy and resource-limited countries.
The study also urges governments and international agencies to prioritize public health campaigns that increase awareness of infection-related cancer risks. Clear communication, the researchers suggest, could help counter misinformation and encourage greater uptake of proven preventive measures.
Given the enormous economic and social costs associated with cancer care, the authors argue that investing in prevention is not only a public health priority but also a sound financial choice. Reducing infection-driven cancers by even a modest proportion could spare hundreds of thousands of people from a cancer diagnosis each year.
Although the new estimates are subject to the usual uncertainties associated with global data, they reinforce a consistent message: preventing and treating certain infections represents one of the most powerful and underused opportunities for reducing future cancer rates worldwide.