Infections Cause 1 in 8 Cancer Cases Globally, New Study Finds

Infections' Role in Global Cancer Burden

New research published in The Lancet Oncology indicates that infections are responsible for a substantial portion of new cancer cases globally. The study, conducted by a team at the International Agency for Research on Cancer (IARC), an arm of the World Health Organization, estimates that 2.3 million new cancer cases in 2024, or 12% of all new cases, were caused by various infectious agents.

Key Infectious Agents Identified

The study found that the bacterium Helicobacter pylori was linked to the largest number of infection-attributed cancer cases, accounting for 760,000 cases, primarily stomach cancer in eastern Asia. Human papillomavirus (HPV) followed closely, responsible for nearly 750,000 new cases globally, including all cervical cancer cases and other cancers like anal, vulvar, vaginal, penile, and some head and neck cancers, with high rates in sub-Saharan Africa. Hepatitis B virus (HBV) and hepatitis C virus (HCV) were also significantly linked to liver cancer cases.

Expanded Understanding of Cancer-Causing Infections

For the first time, researchers expanded the list of cancers linked to infections, identifying 16 additional infectious agents. Gary Clifford, a cancer epidemiologist and study co-author, noted that scientific advancements have led to the identification of new cancer-causing infectious agents and increased evidence regarding the range of cancers caused by previously known agents. New agents include HIV's link to cervical cancer and Merkel cell polyomavirus, which can lead to an aggressive form of skin cancer. The study also recognized the role of the Epstein-Barr virus.

Methodology

To arrive at these figures, researchers first identified which infections cause cancer. They then calculated the fraction of these cancers attributable to specific infections and applied these calculations to global databases of new cancer cases.