One in eight cancers are likely caused by an infection worldwide, new study finds

A recent study from the World Health Organization (WHO) reveals that around 12% of worldwide cancer cases in 2024 may have been caused by infections, with the majority linked to five specific pathogens. The study, published in The Lancet Oncology, identified Helicobacter pylori (4%), human papillomavirus (4%), hepatitis B (2%), Epstein-Barr virus (1%) and hepatitis C (under 1%) as the primary culprits.

These infections are responsible for over 20 types of cancer, including stomach, liver, blood and cervical cancers. Though the proportion of cancer cases caused by infections slightly dropped between 1990 and 2002, the new figures cannot be confidently compared due to changes in data sources and quality. Infections can lead to cancer through several mechanisms, including altering host cell genes, inserting viral DNA into host DNA, and carrying oncogenes.

Infections also cause cancer indirectly through chronic inflammation and tissue damage. The study highlights that preventing infections could significantly reduce cancer rates, particularly in low- and middle-income countries where 75% of infection-related cancers occur. Vaccination programs, such as the HPV vaccine in Australia, have shown promising results in reducing infection rates and preventing associated cancers.