One in eight cancer cases in the world is linked to viruses, bacteria and other infections that affect millions each year, according to new research.
About 2.3 million new cancer cases in 2024 were tied to a dozen familiar infectious agents, an International Agency for Research on Cancer review of 2024 data shows.
“The largest contributors were Helicobacter pylori, human papillomavirus (HPV), hepatitis B virus (HBV), Epstein–Barr virus (EBV) and hepatitis C virus (HCV),” the agency said in a Q&A posted online.
The infections account for almost all cancers caused by infections.
Contagious, stomach lining-attacking Helicobacter pylori, also known as H. pylori, was responsible for the greatest number of cases: some 760,000, followed by sexually transmitted HPV, at 750,000, 260,000 for saliva-shared Epstein-Barr and 160,000 for hepatitis C virus, which is passed through exposure to infected blood.
H. pylori was tied to stomach cancer cases, HPV was tied to cervical cancer cases and Epstein-Barr was linked to nasopharyngeal cancer and some gastric cancers, as well as Hodgkin lymphoma.
Other responsible infections include HBV and HCV, which were linked to liver cancer cases.
And the estimates may even be “very conservative,” Dr. Patrick Moore, chair in Innovative Cancer Research at the University of Pittsburgh, told Newsweek on Monday.
Infection is a "much more important factor in cancer than most people recognize and the importance of each specific infection is highly related to geography,” he said.
More than 626,000 Americans are projected to die from cancer this year, according to the American Cancer Society.
Scientists have long tied infections to cancer — but these findings suggest that more work to prevent the infections is needed to reduce cases, the researchers said.
Most infection-related cancers can already be prevented through public health measures, like vaccination against HPV and HBV. But social, political and economic barriers to access remain.
They offered several solutions, including scaling up interventions, such as HPV vaccinations and tests for infectious agents, as well as access to condoms and cancer screening.
The data also supports investing in research to create prevention tools that aren’t yet available, such as vaccines against Epstein-Barr virus and H. pylori.
“This updated analysis shows that the landscape of infection-related cancers continues to evolve as scientific evidence advances,” Dr. Gary Clifford, senior co-author of the study, said in a release.
“It also highlights where future investments in new prevention tools could have the greatest impact, particularly for infections such as EBV, for which effective vaccines are not yet available.”
