A comprehensive study published in The Lancet Oncology reveals that an estimated 2.3 million new cancer cases worldwide in 2024 were linked to infectious agents. According to the International Agency for Research on Cancer (IARC), which is the cancer agency of the World Health Organization, this figure represents approximately 12 percent—or about one in every eight—of all new cancer diagnoses globally.
Global Cancer Burden Linked to Infections
Researchers noted that the analysis provides an up-to-date picture of the cancer burden associated with infections by including additional infectious agents such as HIV and Merkel cell polyomavirus. The findings also incorporate newly established infection-cancer associations, including recent evidence connecting the Epstein–Barr virus with gastric cancer.
Primary Infectious Agents and Associated Cancers
The scientific review identified twelve infectious agents classified as carcinogenic to humans. However, five primary agents were responsible for the vast majority of infection-related cancer cases, according to findings reported by Al Ghad.
* Helicobacter pylori: Topped the list with approximately 760,000 cases, primarily linked to stomach cancer. * Human Papillomavirus (HPV): Accounted for about 750,000 cases, largely associated with cervical cancer as well as anal, vulvar, vaginal, and certain head and neck cancers. * Hepatitis B Virus (HBV): Linked to roughly 360,000 cases, predominantly liver cancer. * Epstein–Barr Virus (EBV): Accounted for about 260,000 cases, mainly including nasopharyngeal carcinoma and certain stomach cancers. * Hepatitis C Virus (HCV): Associated with approximately 160,000 cases, mostly liver cancer.
Dr. Patrick Moore, director of the Cancer Virology Program at the University of Pittsburgh, described the one-in-eight ratio as comparable to the proportion of lung cancer among total cancer cases in the United States, calling it a significant public health issue. Moore added that the IARC estimates may be very conservative, meaning the actual proportion could be higher.
Geographic Disparities and Risk Factors
The burden of infection-related cancers varied substantially across different regions of the world. East Asia recorded the highest number of such cases, driven largely by the prevalence of Helicobacter pylori and Hepatitis B. Meanwhile, sub-Saharan Africa experienced a high burden of infections, particularly from HPV and other viruses.
Overall, more than three-quarters of all infection-linked cancer cases occurred in low- and middle-income countries. Researchers noted that these disparities stem from differences in infection prevalence, socioeconomic conditions, and access to prevention and treatment services.
Prevention and Future Outlook
Study authors emphasized that the cancer itself is not contagious, but rather that chronic infections can cause cellular changes and inflammation that increase cancer risk over time. Importantly, a substantial portion of these cases can be prevented through existing tools, including vaccination against HPV and Hepatitis B, alongside screening and treatment for infections such as Helicobacter pylori and Hepatitis C.
Researchers have called for policymakers and health systems to expand vaccination, screening, and treatment programs, while also investing in new preventive tools—such as a targeted vaccine for Epstein–Barr virus, which currently lacks an approved immunization.
