A recent study published in The Lancet Oncology reveals that infections play a significant role in causing cancer, with one in eight new cancer cases globally attributed to viruses, bacteria, and other microbes. The research, conducted by The International Agency for Research on Cancer (IARC), estimated that in 2024, approximately 2.3 million new cancer cases, accounting for 12% of all cases, were linked to infectious agents.
The study identified Helicobacter pylori as the leading cause of cancer cases globally, particularly in eastern Asia, where it is associated with an increased risk of stomach cancer. Human papillomavirus (HPV) was also a major contributor, responsible for nearly 750,000 new cancer cases worldwide, including cervical, anal, vulvar, vaginal, penile, and some head and neck cancers, with high incidence rates in sub-Saharan Africa. Hepatitis B virus (HBV) and hepatitis C virus (HCV) were linked to a significant number of liver cancer cases.
Researchers expanded the list of cancers linked to infections to include 16 additional types, highlighting the evolving understanding of the role of infectious agents in cancer development. Some newly identified infectious agents include HIV’s association with cervical cancer and Merkel cell polyomavirus’s connection to aggressive skin cancer.
The study emphasized the growing recognition of Epstein-Barr virus (EBV), which was linked to about 260,000 cancer cases globally in 2024, contributing to nasopharyngeal cancer, some gastric cancers, and Hodgkin’s lymphoma. Notably, EBV has also been implicated in the development of multiple sclerosis.
The report underscores regional disparities in cancer burden, with higher-income countries benefiting from established screening and vaccination programs. In contrast, lower- and medium-resourced countries face challenges in accessing prevention and treatment services, highlighting the need for global efforts to address these disparities.
In Canada, a 2019 study estimated that infections account for four percent of cancer cases, with over 7,000 cancer diagnoses annually attributed to infections. While the prevalence of infection-related cancers is lower in Canada, efforts to increase vaccination rates and screening are crucial for cancer prevention.
Helicobacter pylori remains a significant concern in Canada, with experts advocating for universal screening programs to detect and treat the bacterium, which is a major risk factor for stomach cancer. Strategies to target high-risk groups, such as those with a family history of stomach cancers or specific communities, could help mitigate the impact of infection-related cancers.
Overall, the study highlights the complex interplay between infections and cancer development, emphasizing the importance of preventive measures and early detection in reducing the global cancer burden.