A recent study revealed that infections play a significant role in causing cancer, with one in eight cancer cases globally attributed to various viruses, bacteria, and other microbes. The findings, published in The Lancet Oncology, estimated that around 2.3 million new cancer cases in 2024, representing 12% of all new cases, were linked to infectious agents.
Researchers from The International Agency for Research on Cancer (IARC), a branch of the World Health Organization, conducted the study and identified Helicobacter pylori as the leading cause of infection-related cancer cases worldwide. This bacterium, known to elevate the risk of stomach cancer, was responsible for 760,000 cases, predominantly in eastern Asia.
Human papillomavirus (HPV) was another major contributor, accounting for nearly 750,000 new cancer cases globally, with high incidence rates in sub-Saharan Africa. Additionally, hepatitis B virus (HBV) and hepatitis C virus (HCV) were associated with a significant number of liver cancer cases.
The study also expanded the list of cancers linked to infections, identifying 16 additional types. Gary Clifford, a cancer epidemiologist and co-author of the study, noted advancements in understanding the cancer-causing potential of infectious agents, including new associations such as HIV and cervical cancer, as well as Merkel cell polyomavirus and skin cancer.
Epstein-Barr virus (EBV) emerged as a key infectious agent, linked to about 260,000 cancer cases globally in 2024, contributing to nasopharyngeal cancer, some gastric cancers, and Hodgkin’s lymphoma. EBV was also recognized for its role in multiple sclerosis, highlighting the need for preventive strategies against this virus.
The report emphasized regional disparities in cancer burden due to infections, with high-income countries showing better outcomes compared to lower-resource regions. In Canada, a 2019 study led by epidemiologist Karena Volesky estimated that infections accounted for four percent of cancer cases, underscoring the importance of addressing these risk factors.
Efforts to combat infection-related cancers in Canada include promoting HPV vaccination to prevent cervical cancer. While vaccination programs have led to declining cervical cancer rates, recent stagnation raises concerns about achieving elimination targets by 2040. Enhancing vaccination and screening rates remains crucial to reducing the impact of infectious agents on cancer incidence.
In conclusion, understanding the role of infections in cancer development is vital for implementing effective prevention and screening strategies to reduce the global burden of infection-related cancers.
