About 1 in 8 cases of cancer are caused by viral, bacterial or parasitic infections, according to a new study, suggesting that one of the most effective ways to reduce cancer rates may be to prevent common infections.
In a new analysis published September 28 in the journal The Lancet Oncologyresearchers mapped the global impact of 12 cancer-causing pathogens. They estimate that infections led to about 2.3 million new cases of cancer in 2024, or about 12% of all cancer cases diagnosed that year.
The study highlights that a large proportion of cancer cases could be avoided if these underlying infections were prevented, Dr. Prashant Mathurdirector of India’s National Center for Disease Informatics and Research, who was not involved in the study, told Live Science in an email.
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“When combined with other risk factors such as smoking, alcohol consumption, proper diet, physical activity and environmental pollution, it is estimated that around 50 to 60 percent of all cancers in India are preventable,” he said. Previous studies suggest that similar figures are valid globally.
In the new study, researchers used the Global Cancer Observatory’s GLOBOCAN database, which combines data from various cancer registries, to estimate that around 20 million new cases of cancer will be diagnosed in 2024. The team combined this information with other published data examining the prevalence of different infections in people with specific cancers. This allowed them to estimate how many cases were attributable to each infection.
Their analysis focused on 12 cancer-related pathogens, including human papillomavirus (HPV), hepatitis B and C, HIV and Epstein-Barr virus (EBV), the virus that causes mononucleosis. The resulting breakdown revealed that just four pathogens accounted for about 92% of cancer cases caused by infections.
A bacteria called Helicobacter pyloriwhich infects the gastrointestinal tract, accounted for 760,000 cases, mainly gastric cancers. The other three main cancer triggers were viruses. HPV accounted for 750,000 cases, including cervical, penile, throat and mouth cancers. The hepatitis B virus, which attacks the liver, was responsible for 360,000 cases and EBV for 260,000 cases. (EBV is known to increase the risk of throat cancers, as well as certain lymphomas and stomach cancers.)
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The magnitude of the burden contrasts with the gaps in prevention. By 2024, only 31% of eligible adolescent girls worldwide have received at least one dose of the HPV vaccine, well below the goal of 90%. World Health Organization reports. The degree of protection conferred by the vaccine is striking in countries that have achieved higher coverage.
“We have now reached a crucial milestone: cervical cancer is starting to disappear in countries that have quickly achieved vaccination rates above 80 percent,” said Dr. Rebecca Perkinsan obstetrician-gynecologist at Tufts University School of Medicine who was not involved in the study. “Research in Australia, England“, and Finland showed no cases of HPV-related cancer or death in young adults vaccinated before age 13,” Perkins told Live Science in an email.
But these successes are concentrated in rich countries. The Lancet study found that low- and middle-income countries bear 77% of the global cancer burden from infections. For example, about 81% of HPV-related cancers occurred in these countries.
Perkins pointed out that switching from the standard two-dose HPV vaccine series to a single-dose regimen using the same vaccines could facilitate mass campaigns worldwide by reducing costs and eliminating the need to follow patients for follow-up. The single-dose approach has been supported by recent trials.
As with HPV, there is a very effective vaccine for hepatitis B that can help prevent both infection and associated cancers.
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In the United States, progress has been uneven across states, with some benefiting from high vaccination rates and others lagging behind. One obstacle is that some children’s caregivers believe the injections are unnecessary or that their children are too young to receive them. “The biggest misconception among families is that the HPV vaccine is not necessary or that it can wait,” Perkins noted. “The reality is that you cannot vaccinate too early, only too late.”
There is also a very effective vaccine against hepatitis B, and health officials recommend giving children their first dose as soon as possible after birth. (The US Centers for Disease Control and Prevention recently made the decision to stop recommending universal vaccination at birthwhich experts say could increase rates of hepatitis B infection and related cancers in the country.)
Although the challenge for HPV and hepatitis B is to scale up the use of their vaccines, there is not yet an approved vaccine for EBV.
“The biggest obstacle has been the complexity of the virus,” said Claire Shannon Lowetumor virologist at the University of Birmingham in the United Kingdom, who was not involved in the study. “Unlike many other viruses that use only one or two viral proteins to enter cells, EBV uses multiple proteins…and hides inside cells for our entire lives.”
Epstein-Barr infections are also incredibly common, with up to 95% of people infected as adults; Most people infected with the virus do not develop a related cancer, but it is still a major contributor to the global cancer burden. The germ has also been linked to several autoimmune diseases, which could help spur vaccine development, Shannon-Lowe suggested.
“With the increased momentum that followed Association of EBV with multiple sclerosis and lupus, we may finally have our sights set on a potential vaccine that could not only prevent viral infection, but could also help treat EBV-associated cancers,” she said.
For H. pyloriMeanwhile, researchers study the entire population screening and treatment for infection to help prevent gastric cancer, while vaccine development remains an area requiring additional investment.
The true magnitude of the infection-related cancer burden may be even greater than the study suggests. Some of the registries used in the new research cover only about 19% of the world’s population and only 2% of Africa’s population. Additional high-quality data are needed to fill these gaps.
For Mathur, however, the bottom line is that cancer prevention makes economic sense.
“Studies have clearly demonstrated that the return on investment for cancer prevention is much higher than that for long-term treatment,” he said. “Preventive aspects must be strengthened to achieve long-term gains.”
This article is for informational purposes only and is not intended to offer medical advice.
Rumgay, H., Georges, D., Huang, Y., Hirabayashi, M., Shah, R., de Martel, C., Park, JY, Soerjomataram, I. and Clifford, GM (2026). Global cancer burden attributable to infections in 2024: an analysis of global incidence. The Lancet Oncology, 27(10), 1237-1248. https://doi.org/10.1016/s1470-2045(26)00307-4
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