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A study in The Lancet Oncology estimates that infections with 12 pathogens were linked to 2.3 million cancer cases worldwide in 2024, about 12% of the total. Four pathogens—H. pylori, HPV, hepatitis B and Epstein-Barr virus—accounted for roughly 92% of infection-attributed cases. Vaccines can prevent some of these infections, but access and coverage remain uneven.
Infections caused by viruses, bacteria and parasites were linked to about 2.3 million new cancer cases worldwide in 2024, or roughly 12% of all cases, according to a global analysis published Sept. 28 in The Lancet Oncology. The findings point to vaccination and other infection-prevention measures as potential ways to reduce some cancers, though the study estimates the burden rather than tracking individual cases to prove causation.
Researchers assessed 12 cancer-associated pathogens, using estimates of new cancer cases from the Global Cancer Observatory’s GLOBOCAN database alongside published data on infections found in people with particular cancers. GLOBOCAN estimated that about 20 million new cancers were diagnosed worldwide in 2024. The team used the combined information to estimate how many cases were attributable to each pathogen.
Four pathogens accounted for roughly 92% of infection-linked cases. Helicobacter pylori, a bacterium that infects the digestive tract, was associated with about 760,000 cases, primarily gastric cancers. HPV was linked to about 750,000 cases, including cervical, penile, mouth and throat cancers. Hepatitis B accounted for an estimated 360,000 cases, and Epstein-Barr virus (EBV) for about 260,000.
The analysis also highlights gaps in prevention. The World Health Organization reports that in 2024, 31% of eligible adolescent girls worldwide received at least one HPV vaccine dose, short of its 90% target. The study found that low- and middle-income countries accounted for 77% of the infection-related cancer burden; about 81% of HPV-linked cancers occurred in those countries.
Prevention Could Reduce Cancer Risk
The findings focus attention on cancer risks that can be reduced by preventing infections. Vaccines against HPV and hepatitis B can prevent infections associated with several cancers. H. pylori can be detected and treated, although the study does not estimate how many cancers a particular prevention or treatment program would avert.
Dr. Prashant Mathur, director of India’s National Centre for Disease Informatics and Research, who was not involved in the study, told Live Science that a large share of cancers could be avoided by addressing underlying infections alongside other risk factors. He said estimates for India put the proportion of avoidable cancers at 50% to 60% when infection prevention is combined with action on tobacco, alcohol, diet, physical activity and environmental pollution. That is a broader estimate, not a result measured by this study.
Uneven vaccine coverage means the potential benefits are not shared equally. Dr. Rebecca Perkins, an obstetrician-gynecologist at Tufts University School of Medicine who was not involved in the analysis, said that countries with high HPV vaccination rates have seen signs of cervical cancer beginning to disappear. She cited research from Australia, England and Finland reporting no HPV-related cancers or deaths in young adults vaccinated by age 13. Those findings concern particular populations and do not mean vaccination eliminates cancer risk for everyone.
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Four Pathogens Dominate the Estimate
The study’s pathogen list included HPV, hepatitis B and C, HIV and EBV, among others. These infections do not affect every infected person in the same way: infection can raise cancer risk, but most people with EBV, for example, do not develop an EBV-related cancer. The figures describe estimated population-level cases associated with pathogens, not the risk for an individual patient.
Prevention differs by pathogen. HPV and hepatitis B have vaccines, while there is no approved EBV vaccine. Tumor virologist Claire Shannon-Lowe of the University of Birmingham, who was not involved in the study, told Live Science that EBV’s multiple proteins involved in entering cells and its ability to persist inside the body make vaccine development challenging.
Perkins has said that a single-dose HPV vaccination approach, supported by recent trials, could simplify campaigns by lowering costs and removing the need to track people for a second appointment. Whether and how programs adopt that approach depends on health authorities and local circumstances. Coverage, access and national recommendations vary between countries.
“The biggest misconception from families is that the HPV vaccine is not needed or that it can wait.”
— Dr. Rebecca Perkins, Tufts University School of Medicine, speaking to Live Science
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Limits of the Global Estimates
The study provides estimates, not a count of individually confirmed cases. Its calculations combine cancer-registry data with published evidence on infection prevalence and cancer associations. The resulting figures depend on the quality and coverage of those underlying data, which can vary between countries.
The analysis does not establish that every cancer in a person with one of these infections was caused by that infection, nor does it calculate precisely how many future cases would be prevented by a particular vaccination campaign. It also does not show that all 12 pathogens have vaccines or equally effective prevention options. EBV, in particular, has no approved vaccine.
The source report does not provide a detailed country-by-country breakdown of every pathogen’s contribution, or a projection of how quickly the global total might change if vaccine coverage rises. The 2024 figures are estimates for that year, not a forecast.
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Coverage and Vaccine Research
The immediate public-health focus is likely to remain on expanding HPV and hepatitis B vaccination and reducing barriers to access. The study’s estimates underline the scale of the burden, while the WHO’s coverage figures show how far HPV vaccination remains from its global target. The report does not announce a new vaccination policy or set a specific timetable for changes.
Researchers are also continuing to investigate an EBV vaccine. Shannon-Lowe told Live Science that the virus’s biology complicates development; the analysis gives no date for a vaccine becoming available. Further work will also be needed to refine estimates across regions and assess how changes in prevention affect cancer rates over time.
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Key Questions
What does “one in eight cancer cases” mean?
It refers to the study’s estimate that infections with the 12 pathogens it assessed were linked to about 2.3 million of roughly 20 million new cancer cases worldwide in 2024, or around 12%. It is a global estimate, not an individual’s probability of developing cancer.
Which infections accounted for most of the cases?
H. pylori, HPV, hepatitis B and EBV together accounted for roughly 92% of the infection-attributed cancer cases in the analysis. H. pylori and HPV were each linked to about three-quarters of a million cases.
Can vaccines prevent infection-related cancers?
HPV and hepatitis B vaccines can prevent infections associated with some cancers. The study did not calculate how many cases a specific vaccination program would prevent. There is currently no approved EBV vaccine.
Where was the infection-related cancer burden highest?
The study estimated that low- and middle-income countries accounted for 77% of the global infection-driven cancer burden. About 81% of HPV-linked cancers occurred in those countries.
Source: fediverse
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