Global Study: One in Eight Cancers Caused by Infections

Five Pathogens Driving Global Cancer Incidence

The study highlights a concentration of risk linked to a small group of infectious agents. Helicobacter pylori and HPV each account for 4% of total cancer cases, while hepatitis B contributes 2%, Epstein-Barr virus accounts for 1%, and hepatitis C is linked to less than 1%. According to Gary Clifford, a senior author and epidemiologist at the International Agency for Research on Cancer, these findings identify "actionable risk factors" that can be managed through testing and vaccination. While previous research has tracked these trends since 1990, authors note that direct historical comparisons are difficult due to evolving data collection methods.

Biological Mechanisms Linking Infection to Malignancy

Viruses contribute to cancer primarily by altering the genetic integrity of host cells. They can disable tumor-suppressing proteins like TP53 or RB, which normally regulate cell division and programmed cell death. In other instances, a virus may insert its own DNA into the host cell, disrupting genes that control growth, or introduce oncogenes that directly trigger cancerous transformation.

Bacteria and parasites, such as Opisthorchis viverrini (a liver fluke), operate through indirect pathways. Chronic infection from these organisms induces persistent inflammation, which stresses tissues. This environment can lead to DNA damage or errors during rapid cell regeneration, eventually causing the genetic mutations necessary for cancer development.

Geographic Disparities in Cancer Prevention Access

Approximately 75% of infection-related cancers occur in low- and middle-income countries. Researchers attribute these higher rates in regions like sub-Saharan Africa to disparities in healthcare investment, including limited access to screening programs and preventative interventions. While vaccines and treatments exist for conditions like hepatitis B, hepatitis C, and H. pylori, the lack of widespread, equitable infrastructure remains a significant hurdle in reducing the global cancer burden.

The Role of Vaccination in Cervical Cancer Elimination

Vaccination programs serve as a primary tool for cancer prevention. In Australia, the HPV vaccine program introduced in 2007 has contributed to a 90% reduction in HPV infections among eligible groups, putting the country on track to potentially eliminate cervical cancer by 2035. However, experts warn that maintaining high coverage is essential; vaccination rates for 15-year-olds in Australia fell from 85.7% in 2020 to 79.5% in 2024. Oncologist Nancy Lee of Memorial Sloan Kettering Cancer Center emphasizes that HPV vaccination remains critical for preventing not only cervical cancer but also rising cases of throat cancer associated with the virus.

Frequently Asked Questions About Infection-Related Cancers

How do infections lead to cancer? Infections cause cancer through direct genetic interference—where viruses mutate cell DNA—or indirectly, where chronic inflammation from bacteria or parasites damages tissues over time, leading to mutations during cell repair.

Which cancers are most commonly linked to infection? The pathogens identified in the WHO research are linked to over 20 types of cancer, including stomach, liver, blood, and cervical cancers.

Can these cancers be prevented? Yes. Many are preventable through vaccination, such as the HPV and hepatitis B vaccines, as well as through antibiotic treatments for H. pylori and consistent disease screening programs.

Did you know? The Epstein-Barr virus, once primarily associated with nasal pharyngeal cancers and specific lymphomas, has recently been linked to certain types of stomach cancer in updated research findings.