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A study published in The Lancet Oncology estimates that infections with 12 pathogens accounted for about 2.3 million of the 20 million cancer cases diagnosed worldwide in 2024. HPV, Helicobacter pylori, hepatitis B and Epstein-Barr virus together made up about 92% of infection-attributed cases; researchers and experts say prevention is possible, but access and vaccine coverage remain uneven.
A global analysis published Sept. 28 in The Lancet Oncology estimates that infections caused about 2.3 million cancer cases in 2024, roughly 12% of the 20 million cases diagnosed worldwide. The study links those cancers to 12 viruses, bacteria and parasites, and points to prevention—including vaccination against HPV and hepatitis B—as one way to reduce some cancer risk.
Researchers used estimates from the Global Cancer Observatory’s GLOBOCAN database, which draws on cancer registry data, alongside published evidence about infections found in people with particular cancers. They used those sources to estimate how many cancers could be attributed to each pathogen. These are estimates of cases associated with infections, not a count of individually verified causes for every patient.
Four pathogens accounted for about 92% of the infection-attributed cases. Helicobacter pylori, a bacterium that infects the digestive tract, was linked to an estimated 760,000 cases, mainly gastric cancers. HPV was linked to 750,000 cases, including cervical, penile, throat and mouth cancers. Hepatitis B was linked to 360,000 cases, and Epstein-Barr virus to 260,000. The remaining cases were attributed to eight other pathogens in the analysis.
The study’s findings do not mean that every infection leads to cancer. Many infections are common, while only a fraction of infected people develop related cancers. The analysis estimates the burden across populations; individual risk varies with factors including the pathogen, duration of infection and other health or environmental influences.
Prevention Could Reduce Some Cancer Risk
The estimate matters because at least some infection-related cancers can be prevented through vaccination, screening and treatment of infections. HPV and hepatitis B vaccines target two of the four pathogens linked to the largest numbers of cases in the analysis. The findings put the potential public-health benefit in global terms, while also showing that vaccines are only one part of cancer prevention.
HPV vaccine coverage remains far below the World Health Organization’s target: in 2024, 31% of eligible adolescent girls worldwide had received at least one dose, compared with the WHO’s 90% target. The study also found that low- and middle-income countries accounted for 77% of infection-driven cancer cases; about 81% of HPV-linked cancers occurred in those countries. Those figures indicate a substantial gap between the burden and access to prevention.
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 preventing infections could contribute to reducing cancer cases alongside measures addressing tobacco, alcohol, diet, physical activity and pollution. The analysis does not establish that vaccination alone would prevent a particular share of all cancers.
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Vaccination Coverage and Uneven Access
The four leading pathogens differ in how they cause cancer and how they can be addressed. HPV vaccination is used to prevent infections with cancer-causing strains of the virus. Hepatitis B vaccination prevents infection with a virus that can lead to liver cancer. H. pylori and EBV do not currently have vaccines in routine use for cancer prevention, so their contributions require other prevention and research approaches.
Experts cited in the report described evidence of falling HPV-related disease where vaccination coverage is high. Dr. Rebecca Perkins, an obstetrician-gynecologist at Tufts University School of Medicine who was not involved in the study, said countries that quickly reached vaccination rates above 80% had reached “the critically important milestone of cervical cancer starting to disappear.” She also cited research from Australia, England and Finland reporting no HPV-related cancers or deaths among young adults vaccinated by age 13. Those statements refer to findings in particular populations and should not be read as a guarantee for every vaccinated person.
Perkins said a single-dose HPV schedule, supported by recent trials, could make vaccination campaigns easier by reducing costs and the need for follow-up appointments. In the United States, she said, some caregivers believe the vaccine is unnecessary or can be delayed. For hepatitis B, vaccine recommendations and policies differ by country; the source report notes a recent CDC change to its U.S. recommendation for universal vaccination at birth.
“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 estimates the number of cancers attributable to infection by combining cancer totals with previously published infection data. It does not identify the cause of each individual cancer, and the result depends on the quality and coverage of the underlying registries and research. The supplied report does not provide confidence intervals or a detailed breakdown of uncertainty for each pathogen, so the figures should be understood as estimates rather than exact counts.
It is also unclear how quickly expanded vaccination or other infection-prevention measures would change cancer rates. Many cancers develop years after infection, and vaccine coverage, access to diagnosis and treatment, and local patterns of infection vary widely. The analysis identifies a potential prevention opportunity; it does not measure the effects of a particular vaccination campaign.
Most people infected with EBV do not develop a related cancer, according to the report, and as many as 95% of people are infected by adulthood. There is no approved EBV vaccine. Shannon-Lowe said the virus uses multiple proteins to enter cells and can persist inside the body, adding to development challenges. When or whether a vaccine will become available remains unknown.
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Coverage and Vaccine Research
The near-term public-health question is whether countries can increase delivery of existing HPV and hepatitis B vaccines, particularly in places carrying a large share of infection-related cancer cases. WHO’s 90% HPV vaccination target offers a benchmark against the reported 31% coverage among eligible adolescent girls in 2024. The study itself does not set a new policy target or announce a program.
Researchers and health authorities are also tracking whether single-dose HPV schedules can support wider campaigns, while vaccine research continues for pathogens such as EBV. The available source material does not give a specific next publication date or development milestone. Further estimates and implementation data will be needed to show whether increased prevention is reducing infection-related cancer incidence across countries.
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Key Questions
What does the study mean by 1 in 8 cancer cases?
The researchers estimate that infections accounted for about 2.3 million of roughly 20 million cancer cases worldwide in 2024, or around 12%. It is a population-level estimate, not a finding that infection caused every cancer in that group with individual certainty.
Which infections were linked to the most cases?
The four leading pathogens were H. pylori, HPV, hepatitis B and Epstein-Barr virus. Together, they accounted for about 92% of the infection-attributed cases in the analysis.
Can vaccines prevent all infection-related cancers?
No. Vaccines can prevent some infections associated with cancer, including HPV and hepatitis B, but there is no approved EBV vaccine, and the source report does not identify a vaccine for H. pylori. Vaccination is one part of prevention, not a guarantee against cancer.
Why are the estimates not exact counts?
The team combined global cancer estimates with published data on infections associated with specific cancers. The result is an estimate of population-level attribution; registry coverage and available infection research vary, and the analysis does not establish the cause of each individual case.
Source: fediverse
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