A recent study published in The Lancet Oncology reveals that infections play a significant role in causing cancer, with one in eight cancer cases worldwide attributed to various viruses, bacteria, and other microbes. The research, conducted by The International Agency for Research on Cancer (IARC), identified 2.3 million new cancer cases in 2024 linked to infectious agents, comprising 12% of all new cancer cases.
The study found that Helicobacter pylori, a bacterium known to increase the risk of stomach cancer, was responsible for the largest number of cancer cases globally, with 760,000 cases, mainly in eastern Asia. Human papillomavirus (HPV) was another major contributor, causing nearly 750,000 new cases worldwide, particularly in sub-Saharan Africa. Hepatitis B virus (HBV) and hepatitis C virus (HCV) were also associated with a significant number of liver cancer cases.
Furthermore, the research expanded the list of cancers linked to infections by identifying 16 additional ones, including HIV’s connection to cervical cancer and Merkel cell polyomavirus causing an aggressive form of skin cancer. The study methodology involved examining cancer-causing infections, calculating their contribution to specific cancers, and applying these calculations to global databases of new cancer cases.
The study also highlighted the growing recognition of Epstein-Barr virus (EBV), which was linked to approximately 260,000 cases globally in 2024, leading to nasopharyngeal cancer, some gastric cancers, and Hodgkin’s lymphoma. EBV is also implicated in the development of multiple sclerosis, for which there are currently no specific treatment tools available.
The report emphasized regional disparities in cancer rates, with high-income countries showing better outcomes due to established screening and vaccination programs compared to lower-resource countries. In North America, infections like H. pylori and HPV are the primary cancer sources.
In Canada, a 2019 study estimated that four percent of cancers were attributable to infections, leading to over 7,000 cancer diagnoses annually. Efforts to increase HPV vaccination rates and cervical cancer screening aim to reduce the burden of infections causing cancer in the country.
Overall, the findings underscore the significant impact of infections on cancer development and the importance of preventive measures, such as vaccination and screening programs, to reduce the global burden of infection-related cancers.