Approximately one in eight cancers diagnosed globally is linked to infections from viruses, bacteria, or parasites, according to a new analysis published September 28 in The Lancet Oncology. Researchers calculated that these infectious agents were responsible for an estimated 2.3 million new cancer cases in 2024, representing roughly 12% of all malignancies identified that year.
The study utilized data from the Global Cancer Observatory’s GLOBOCAN database, which projects that nearly 20 million new cancer cases were diagnosed worldwide in 2024. By cross-referencing this with existing prevalence data, the team quantified the cancer burden attributable to 12 specific pathogens. Four of these microbes alone accounted for approximately 92% of infection-related cancers.
Helicobacter pylori, a bacterium affecting the gastrointestinal tract, was the leading cause, responsible for 760,000 cases, predominantly gastric cancers. The remaining top drivers were viral: human papillomavirus (HPV) accounted for 750,000 cases, including cervical, penile, and throat cancers; hepatitis B virus caused 360,000 liver cancer cases; and Epstein-Barr virus (EBV) was linked to 260,000 cases involving throat cancers, lymphomas, and stomach cancers.
Dr. Prashant Mathur, director of India’s National Centre for Disease Informatics and Research, who was not involved in the study, emphasized that a significant portion of cancer could be averted through prevention. When combined with other risk factors such as tobacco, alcohol, diet, physical inactivity, and pollution, he noted that an estimated 50% to 60% of cancers in India are preventable, a figure consistent with global projections.
Despite the availability of effective vaccines, prevention gaps remain substantial. The World Health Organization reports that only 31% of eligible adolescent girls received at least one dose of the HPV vaccine in 2024, falling short of the 90% target. However, nations that have achieved high coverage rates are seeing dramatic results. Dr. Rebecca Perkins, an obstetrician-gynecologist at Tufts University School of Medicine, noted that cervical cancer is beginning to disappear in countries with vaccination rates exceeding 80%. Data from Australia, England, and Finland indicate zero cases of HPV-related cancers or deaths among young adults vaccinated by age 13.
The burden of infection-driven cancer is disproportionately borne by low- and middle-income countries, which account for 77% of the global total. For instance, 81% of HPV-linked cancers occur in these regions. Perkins suggested that transitioning to a single-dose HPV vaccine regimen could facilitate mass campaigns by reducing costs and eliminating the need for follow-up visits, a strategy supported by recent clinical trials.
In the United States, vaccination rates vary significantly by state. Barriers include misconceptions among caregivers that the vaccines are unnecessary or that administration can be delayed. “The reality is that you can’t vaccinate too early, only too late,” Perkins said. While a highly effective hepatitis B vaccine exists, the CDC recently revised its recommendation against universal vaccination at birth, a move experts warn could increase infection and cancer rates.
Currently, no vaccine exists for EBV, though researchers are optimistic. Claire Shannon-Lowe, a tumor virologist at the University of Birmingham, cited the virus’s complexity—specifically its ability to hide in cells for life and utilize multiple proteins for entry—as a major hurdle. However, emerging links between EBV and autoimmune diseases like multiple sclerosis and lupus may accelerate vaccine development.
For H. pylori, scientists are exploring widespread testing and treatment rather than vaccines. The study authors cautioned that the true scale of infection-related cancers may be even higher, noting that the cancer registries used cover only about 19% of the global population and just 2% of Africa. Mathur concluded that investing in prevention offers a far greater return on investment than treatment over the long term.
Zero HPV-related cancers in vaccinated young adults? That’s the proof we need. More people need to hear this success story immediately.
The CDC changing hepatitis B recommendations worries me. Can we really afford to wait years to see if birth vaccinations drop? What about the long-term cancer impact?
I had no idea H. pylori was the leading cause. It’s terrifying how many cancers stem from something as common as a stomach bacteria.
This reinforces why vaccination access in developing nations is so critical. The disparity in cancer rates is heartbreaking yet preventable.