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A study published in The Lancet Oncology estimates that infections caused about 2.3 million of the 20 million new cancer cases diagnosed worldwide in 2024—roughly 12%. Four pathogens accounted for about 92% of infection-attributable cases, while the researchers and outside experts point to prevention gaps, including low HPV vaccination coverage.
A global analysis published Sept. 28 in The Lancet Oncology estimates that infections with viruses, bacteria or parasites caused about 2.3 million of the 20 million new cancer cases diagnosed worldwide in 2024—roughly one in eight. The findings point to infections as a substantial, and in some cases preventable, contributor to cancer, while highlighting that vaccination and other prevention measures are not reaching all populations equally.
The researchers assessed 12 pathogens known to be linked to cancer, combining estimates from the Global Cancer Observatory’s GLOBOCAN database with published data on infections among people with particular cancers. The resulting figures are estimates of cases attributable to infection, rather than a count of cases individually confirmed to have been caused by a pathogen.
Four pathogens accounted for about 92% of the estimated infection-related cases. Helicobacter pylori, a bacterium that infects the stomach and other parts of the gastrointestinal tract, was associated with about 760,000 cases, primarily gastric cancers. Human papillomavirus (HPV) accounted for about 750,000, including cervical, penile, throat and mouth cancers. Hepatitis B was linked to about 360,000 cases, and Epstein-Barr virus (EBV) to about 260,000.
The analysis describes the scale and distribution of infection-associated cancers; it does not establish that every case linked to a pathogen could have been prevented. Prevention options differ by infection. Vaccines are available for HPV and hepatitis B, while there is no approved EBV vaccine, according to the source report. H. pylori infection can also be addressed through detection and treatment, but the supplied material does not quantify how much of its estimated cancer burden could be avoided through those measures.
Prevention Gaps Shape Cancer Burden
The findings matter because some infections associated with cancer can be prevented or treated, giving public health programs options to reduce future risk alongside efforts such as screening and early diagnosis. The study does not measure the effect of any particular vaccination campaign, but its estimates show why improving access to prevention is relevant to cancer control.
HPV vaccination coverage remains well below the global target cited in the source report: in 2024, 31% of eligible adolescent girls worldwide had received at least one dose, compared with a World Health Organization target of 90%. Rebecca Perkins, an obstetrician-gynecologist at Tufts University School of Medicine who was not involved in the study, said countries with high vaccination coverage have begun to see cervical cancer decline. That observation is an expert’s account of progress, not a result measured by the new analysis.
The burden is also unevenly distributed. The study estimates that low- and middle-income countries account for 77% of cancer cases attributed to infections, and about 81% of HPV-linked cancers occurred in those countries. Differences in vaccine access, health services and cancer prevention programs may affect who benefits, although the figures supplied do not identify the contribution of each factor.
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Four Pathogens Drive Most Cases
The researchers’ estimate draws on global cancer incidence data and previously published research on infections associated with specific cancers. The database covers an estimated 20 million new cancer cases in 2024; the study then assessed how many could be attributed to the selected pathogens. Because the analysis combines different data sources, its headline figure is an estimate rather than a direct tally of infection-caused tumors.
HPV and hepatitis B are notable in the report because vaccines are available against both infections. HPV is associated with several cancers, while chronic hepatitis B can lead to liver cancer. The source report says hepatitis B vaccination is highly effective and notes that health officials have recommended an early first dose for infants. It also reports that a U.S. recommendation on universal vaccination at birth recently changed, with experts warning that the change could increase infections and related cancers; the supplied material does not provide further details on the policy or its implementation.
EBV is widespread: the source report says as many as 95% of people are infected by adulthood. Most infected people do not develop an EBV-related cancer, but the virus is linked to certain lymphomas and cancers of the throat and stomach. Claire Shannon-Lowe, a tumor virologist at the University of Birmingham who was not involved in the study, said developing a vaccine is complicated by the virus’s multiple proteins involved in entering cells and its ability to remain in the body.
“The biggest misconception from families is that the HPV vaccine is not needed or that it can wait. The reality is that you can’t vaccinate too early, only too late.”
— Dr. Rebecca Perkins, an obstetrician-gynecologist at Tufts University School of Medicine, who was not involved in the study
Limits of the Global Estimates
The figures are model-based estimates, not a case-by-case determination that infection caused each cancer. The study used cancer registry estimates and published infection data; the supplied report does not give the uncertainty ranges around the 2.3 million total or explain how estimates varied across countries and pathogens.
The analysis identifies cases associated with 12 pathogens, but it does not establish what share would be prevented by vaccination, screening, treatment or other interventions. Nor does the supplied material provide a detailed breakdown of the remaining 8% of infection-attributable cases beyond the four leading pathogens. It is also unclear how the estimates may change as cancer and infection data are updated.
The report notes promising outcomes in some vaccinated populations, but those observations should not be read as evidence that vaccination has eliminated HPV-related cancer worldwide. Coverage remains unequal, and EBV has no approved vaccine, leaving important prevention questions unresolved.
Coverage and Prevention Are Next
The immediate public health challenge is expanding access to established prevention, particularly HPV and hepatitis B vaccination, while addressing gaps in screening and care. Perkins said a single-dose HPV vaccine approach, supported by recent trials cited in the source report, could make campaigns less costly and reduce the need to track people for a follow-up dose. The supplied material does not state which countries have adopted that approach or how quickly broader use may occur.
Researchers and health officials will also need to track whether vaccination coverage rises and whether cancer rates change over time. For EBV, development of a vaccine remains an area of research rather than an available prevention option. The study’s global estimates provide a measure of the infection-linked cancer burden, but progress will depend on how prevention programs are funded and delivered—and on future evidence about their effects.
Key Questions
What does the study mean by one in eight cancer cases?
It estimates that infections with 12 cancer-linked pathogens were attributable to about 2.3 million of the 20 million new cancer cases worldwide in 2024, or roughly 12%. The estimate is not a case-by-case count.
Which infections were linked to the most cancer cases?
The four leading pathogens were H. pylori, HPV, hepatitis B and EBV. Together, they accounted for about 92% of the estimated infection-attributable cases. H. pylori and HPV each accounted for roughly three-quarters of a million cases.
Can infection-related cancers be prevented?
Some risks can be reduced. Vaccines are available for HPV and hepatitis B, while other prevention measures depend on the pathogen and the cancer. The study estimates infection-attributable cases but does not say what proportion could be prevented through any single intervention.
Is there an approved vaccine for Epstein-Barr virus?
No approved EBV vaccine is described in the source report. EBV is common, and most infected people do not develop related cancer; vaccine development remains challenging, according to a tumor virologist quoted in the report.
Source: fediverse
