Infectious agents caused an estimated 2.3 million new cancer cases worldwide in 2024. This accounts for 12 percent of all global cancer diagnoses, according to a report published in The Lancet Oncology by researchers at the International Agency for Research on Cancer (IARC). The landmark study by the World Health Organization arm sheds new light on microbial drivers in oncological research, expanding the tracked list to include 16 additional infectious pathogens alongside historically recognized culprits.
While sun exposure, smoking, and family history frequently dominate discussions surrounding cancer risk factors, the findings emphasize that a significant fraction of the global cancer burden is directly tied to preventable and treatable microbes. Experts note that these infection-linked cancers represent highly actionable targets for public health intervention through widespread vaccination, screening, and antimicrobial therapies.
Leading Pathogens Driving Global Diagnoses
The IARC study identified specific bacteria and viruses responsible for the vast majority of infection-attributed malignancies around the world:
- Helicobacter pylori: This bacterium was identified as the primary culprit, driving approximately 760,000 stomach cancer cases, predominantly concentrated in eastern Asia.
- Human Papillomavirus (HPV): HPV followed closely, driving nearly 750,000 new cases of cervical, anal, vulvar, vaginal, penile, and select head and neck cancers, with high rates observed in sub-Saharan Africa.
- Hepatitis B and C Viruses: HBV and HCV contributed significantly to global liver cancer numbers, with HBV accounting for roughly 360,000 cases and HCV linked to approximately 160,000 cases in 2024.
- Epstein-Barr Virus (EBV): Newly recognized for a broader scope of impact, EBV was linked to about 260,000 cases globally, including nasopharyngeal cancer, specific gastric cancers, and Hodgkin lymphoma.
Gary Clifford, a cancer epidemiologist and study co-author based in Lyon, France, highlighted how scientific understanding has evolved. “There’s been new infectious agents identified in this time as being cancer-causing, and even the infectious agents that we knew about in the past, the evidence has increased about the number of different cancers that they can cause,” Clifford said.
Regional Disparities and Preventable Risks
The global report highlights profound regional differences driven largely by historical disparities in healthcare access. High-income countries that successfully established robust cancer screening and vaccination programs over recent decades fare much better than lower- and medium-resourced countries where preventative tools remain scarce.
Dr. Patrick Moore, chair in Innovative Cancer Research at the University of Pittsburgh, noted that the IARC’s estimates may prove conservative. He emphasized that the fraction of one in eight patients is comparable to the proportion of lung cancer across all U.S. cases, proving that infection-linked malignancies are far from rare or insignificant.
Experts agree that many of these cancers are entirely preventable. Tools such as childhood HPV vaccines, hepatitis immunizations, and simple antibiotic regimens to clear H. pylori bacterial infections offer powerful pathways to reduce incidence rates globally.
Next Steps for Global Health Systems
Public health officials and researchers are calling on policymakers to prioritize scaling up proven interventions. Key recommendations include:
- Expanding universal childhood vaccination programs for HPV and hepatitis B virus.
- Increasing access to routine testing and treatment for H. pylori, hepatitis C, and HIV.
- Strengthening organized cervical cancer screening initiatives, particularly in low- and middle-income regions.
- Combating social stigmas associated with infections like HPV and HIV that deter patients from seeking timely medical evaluation.
With targeted political commitment and equitable access to care, health systems can dismantle the barriers that allow preventable infection-driven cancers to persist worldwide.
