Millions of cancer cases worldwide may be linked to infections that can be prevented or treated, according new research.
Researchers from the International Agency for Research on Cancer estimate that about 2.3 million of the 19.2 million new cancer cases recorded worldwide in 2024 were linked to infections.
Five infections accounted for most of these cases: Helicobacter pylori (H. pylori), human papillomavirus (HPV), hepatitis B, hepatitis C and Epstein-Barr virus (EBV).
The study, published in The Lancet Oncology, found that low- and middle-income countries accounted for about 77 per cent of infection-related cancers.
East Asia recorded the highest number, with about 990,000 cases linked to infections, with H. pylori and hepatitis B identified as the main causes in the region.
The researchers said better infection prevention and treatment could help reduce the number of cancers linked to these infections.
“Although investment in the development of new preventive vaccinations is key, many prevention strategies are known to be cost-effective,” the authors wrote.
“Unfortunately, such strategies are often underused due to societal, financial and political barriers, often in the settings that need them most.”
The researchers highlighted measures including increasing HPV vaccination, improving safe injection practices, increasing access to condoms and HIV prevention drugs, and detecting and treating cervical and anal cancer early.
H. pylori was the biggest infection-related cause of cancer worldwide, accounting for about 760,000 cases in 2024, and most were stomach cancers.
The bacterium is commonly found in the stomach and can spread through contaminated food and water.
Researchers said the development of effective vaccines against H. pylori could help reduce stomach cancer rates, although progress has been slow.
HPV was another major cause of infection-related cancer. The virus is common and usually causes no problems, but some high-risk types can cause changes in cells that eventually lead to cancer.
Almost all cervical cancers are caused by HPV, which is also linked to cancers of the throat, mouth, anus, penis, vulva and vagina.
HPV vaccination and cervical screening are important tools for preventing cervical cancer.
The study also identified EBV as an important cause of cancer. The virus is extremely common and is best known for causing glandular fever, although most people infected with EBV do not develop cancer.
The researchers stressed that infection alone does not necessarily cause cancer, with factors including genetics, overall health and diet also influencing a person’s risk.
“As there are currently no efficient strategies to control infection, EBV should be considered an important target for prevention.”
Several clinical trials are investigating potential EBV vaccines.
Hepatitis B and C together accounted for about one-third of all infection-related cancers, most of them liver cancers.
The researchers said these cancers should be highly preventable because effective treatments are available. Hepatitis B can now be controlled with antiviral medicines, while hepatitis C can now be cured in most people.
The findings highlight how vaccination, screening, safer practices and effective treatment can play a role in reducing some types of cancer worldwide.
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