Infections Cause One in Eight New Cancer Cases

Infections that are often preventable cause approximately 2.3 million new cancer cases worldwide, accounting for roughly one in every eight cases, according to new estimates from the International Agency for Research on Cancer (IARC), part of the World Health Organization (WHO), released on Tuesday.

The study, published in The Lancet Oncology, provides the latest picture of the disease, drawing particularly on advances in understanding the causes of cancer and on expanded, updated global data on incidence rates.

Scientists estimated the proportion of new cancer cases in 2024 attributable to 12 infectious factors, including viruses, bacteria, and parasites.

The WHO specialized agency noted that these five infectious agents are responsible for the overwhelming majority of infection-related cancer cases.

The ranking of Epstein-Barr virus in fourth place reflects growing discoveries regarding the role of this widespread herpes family virus in the development of several types of cancer, including nasopharyngeal cancer, lymphomas, and some stomach cancers.

Dr. Gary Clifford, one of the study’s lead authors, said, “The picture of infection-related cancers continues to change as scientific knowledge advances.”

The study also reveals significant geographic disparities. In East Asia, 42% of global infection-related cancer cases are concentrated, primarily caused by Helicobacter pylori bacteria and hepatitis B virus.

Overall, more than three-quarters of infection-related cancer cases in 2024 were recorded in low- and middle-income countries, where access to prevention and treatment remains uneven.

The study’s authors emphasize that several scientifically proven strategies can prevent most infection-related cancers, including vaccination against human papillomavirus (HPV) and hepatitis B virus, screening and treatment for infections whether caused by Helicobacter pylori, hepatitis viruses, or HIV, as well as the availability of condoms.

However, these preventive measures face ongoing financial, political, or health system-related barriers in many parts of the world.

The agency also calls, alongside prevention efforts, for the development of new tools, particularly vaccines against Epstein-Barr virus and other infectious cancer-causing agents for which effective preventive measures are currently unavailable.