Infection‑Driven Cancers Account for Roughly One‑Eighth of Global Cases, Study Finds

A new study has found that roughly one in eight cancer cases worldwide are caused by infections from viruses, bacteria, or parasites, suggesting that preventing these infections could be a powerful tool for reducing cancer rates.

The analysis, published on Sept. 28 in *The Lancet Oncology*, examined the impact of 12 known cancer‑causing pathogens. Researchers estimate that infections were responsible for about 2.3 million new cancer diagnoses in 2024, representing roughly 12 % of all cancers identified that year.

According to Dr. Prashant Mathur, director of India’s National Centre for Disease Informatics and Research, who was not involved in the research, the findings indicate that many of these infections are preventable and therefore many cancers could be avoided.

He noted that when infections are combined with other risk factors such as tobacco use, alcohol consumption, poor diet, physical inactivity, and environmental pollution, an estimated 50‑60 % of cancers in India are avoidable. Similar proportions are thought to apply globally.

To reach these conclusions, the team utilized the Global Cancer Observatory’s GLOBOCAN database, which aggregates data from cancer registries worldwide. GLOBOCAN reported approximately 20 million new cancer cases in 2024. The researchers cross‑referenced this information with published studies on infection prevalence among cancer patients, allowing them to calculate the number of cases attributable to each pathogen.

The investigation focused on twelve infection‑linked cancers, including human papillomavirus (HPV), hepatitis B and C, HIV, and Epstein‑Barr virus (EBV). The analysis revealed that just four of these pathogens accounted for about 92 % of infection‑driven cancers.

A bacterium, *Helicobacter pylori*, was linked to roughly 760,000 cases, most of which were gastric cancers. HPV was responsible for about 750,000 cases, encompassing cervical, penile, oropharyngeal, and oral cancers. Hepatitis B virus contributed to approximately 360,000 liver cancers, while EBV was associated with around 260,000 cases, increasing the risk of throat cancers, certain lymphomas, and stomach malignancies.

Despite the high burden, vaccination coverage remains limited. In 2024, only 31 % of eligible adolescent girls worldwide received at least one dose of the HPV vaccine, falling far short of the World Health Organization’s 90 % target. Countries that have achieved higher uptake have seen dramatic reductions in vaccine‑preventable cancers.

Dr. Rebecca Perkins, an obstetrician‑gynecologist at Tufts University School of Medicine, highlighted that cervical cancer has begun to decline in nations where vaccination rates exceed 80 %. She cited studies from Australia, England, and Finland showing zero HPV‑related cancers or deaths among young adults who were vaccinated by age 13.

These successes are not evenly distributed; low‑ and middle‑income countries shoulder about 77 % of the global infection‑related cancer burden. For instance, roughly 81 % of HPV‑linked cancers occur in these nations.

To improve access, some experts are advocating a shift from the standard two‑dose HPV vaccine schedule to a single‑dose regimen. This approach could lower costs, simplify logistics, and eliminate the need for follow‑up visits, and recent trials have supported its effectiveness.

In the United States, vaccination rates vary widely by state. A common barrier is parental perception that the vaccine is unnecessary or that children are too young. Dr. Perkins emphasized that the vaccine can be administered early, noting, “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.”

A highly effective hepatitis B vaccine also exists, and health authorities recommend the first dose be given shortly after birth. However, the U.S. Centers for Disease Control and Prevention recently revised its guidance, no longer recommending universal vaccination at birth—a change that experts warn could increase hepatitis B infections and related cancers in the country.

Unlike HPV and hepatitis B, there is currently no approved vaccine for Epstein‑Barr virus. Dr. Claire Shannon‑Lowe, a tumor virologist at the University of Birmingham, explained that the virus’s complexity hampers vaccine development. EBV uses multiple proteins to enter cells and can remain dormant in the body for a lifetime, making it a challenging target.

“The biggest hurdle has been the complexity of the virus,” she said. “Unlike many other viruses that use just one or two virus proteins to enter cells, EBV uses multiple proteins … and it hides inside cells for our entire lifetime.”

Epstein‑Barr virus infects up to 95 % of adults, yet only a small fraction develop associated cancers. The virus has also been linked to autoimmune diseases such as multiple sclerosis and lupus, providing additional motivation for vaccine research. “With the increased impetus following EBV’s association with multiple sclerosis and lupus, we may finally have a potential vaccine in sight that could not only prevent virus infection but could help treat EBV‑associated cancers,” Dr. Shannon‑Lowe added.

For *Helicobacter pylori* infections, researchers are promoting widespread testing and treatment to curb gastric cancer risk, while continued investment is needed to develop an *H. pylori* vaccine.

The true impact of infection‑related cancers may be understated. The study’s data sources cover only about 19 % of the global population, with Africa represented by just 2 %. Expanding high‑quality surveillance will improve our understanding of the full burden.

Dr. Mathur concluded that preventing cancers driven by infections is not only a health imperative but also an economic one. “Studies have clearly demonstrated that the return on investment of prevention on cancers is much higher than on its treatment in the long run,” he said. “Preventive aspects must be strengthened for long-term gains.”

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