Roughly one in eight cancer diagnoses worldwide in 2024 were driven by infections such as human papillomavirus and Helicobacter pylori, according to a global incidence analysis published in The Lancet Oncology. The findings from the World Health Organization’s cancer agency highlight that millions of new cases are potentially preventable through widespread vaccination, screening, and treatment.
Medical researchers have long recognized that certain pathogens can trigger malignant changes in human tissue, but a comprehensive global incidence study sheds new light on the true scale of that toll. Published in The Lancet Oncology, the analysis estimates that 2.3 million new cancer diagnoses globally in 2024—representing about 12 percent of all new cancer cases—stemmed directly from underlying microbial and parasitic infections. The research was led by investigators at the International Agency for Research on Cancer, an arm of the World Health Organization.
While lifestyle factors such as smoking and sun exposure typically dominate public discussions around cancer prevention, infections remain an underappreciated driver of malignant disease. The study focused on 12 specific pathogens classified as Group 1 carcinogens. These infectious agents include viruses, bacteria, and parasites that can induce long-term tissue damage, chronic inflammation, or direct genetic alterations in host cells.
Helicobacter pylori and Human Papillomavirus Drive Most Cases
The vast majority of infection-attributable cancer cases are driven by just a handful of pathogens. Two agents in particular account for roughly 1.5 million of the 2.3 million cases recorded in the study: the stomach bacterium Helicobacter pylori and the sexually transmitted human papillomavirus.
H. pylori was linked to approximately 760,000 gastric cancer cases globally, making it the single largest infectious contributor. Human papillomavirus followed closely behind, driving an estimated 750,000 cases, predominantly cervical cancer, alongside anal, vulvar, vaginal, penile, and head and neck malignancies. Each of these two primary pathogens accounted for roughly 4 percent of all global cancer diagnoses.
Five specific infections accounted for more than 2.2 million of the estimated 2.3 million total infection-attributable cancer diagnoses analyzed by the research team. Beyond the two leading agents, hepatitis B virus, Epstein–Barr virus, and hepatitis C virus made up the remainder of this prominent group. The authors noted that these viruses, bacteria, and parasites can cause more than 20 different types of cancer, including stomach, liver, blood, and cervical cancers.
According to population-level data evaluated in the study, viral hepatitis played a major role in liver cancer incidence worldwide. Patients exposed to these microbial agents experience various biological mechanisms, such as chronic inflammation and repeated tissue damage that increase DNA damage and abnormal cell growth, eventually putting cells on the road toward becoming malignant. The researchers emphasized that while an estimated 80 percent of the population has been exposed to certain types of HPV strains, the human body clears the virus on its own in most cases. However, persistent infections can lead to serious disease.
Cleveland Clinic data indicates that HPV is the most common viral sexually transmitted infection in the United States, infecting roughly 14 million people a year and featuring more than 100 distinct types. Joshua Cohen points out that most cancers are not caused by infection, but certain exposures over a lifetime result in an increased risk of particular malignancies.
- Hepatitis B virus (HBV): Linked to about 360,000 cases, primarily liver cancers (Newsweek).
- Epstein–Barr virus (EBV): Associated with approximately 260,000 cases, including nasopharyngeal cancer, certain gastric cancers, and Hodgkin lymphoma (Newsweek).
- Hepatitis C virus (HCV): Tied to roughly 160,000 cases, mostly liver cancers (Newsweek).
Additional pathogens identified in the analysis include HIV, Kaposi sarcoma-associated herpesvirus, Schistosoma haematobium, human T-cell lymphotropic virus type 1, Opisthorchis viverrini, Clonorchis sinensis, and Merkel cell polyomavirus.
Global Disparities in Prevention and Treatment Access
The study highlights profound geographical inequalities in how infection-related cancers are distributed. Low- and middle-income countries bear roughly three-quarters of the global infection-driven cancer burden. Eastern Asia alone accounted for 42 percent of all infection-attributable cancers worldwide in 2024, driven largely by high regional rates of H. pylori and hepatitis B. Sub-Saharan Africa also recorded a particularly high burden driven by HPV and Kaposi sarcoma-associated herpesvirus, further worsened by HIV.
“Despite advances in vaccination and screening, infection-related cancers continue to pose a significant global problem, with the burden falling unevenly on populations in low- and middle-income countries.”
Harriet Rumgay, a scientist in the agency’s Cancer Surveillance Branch and a co-author of the study
Public health experts emphasize that many of these cancers are preventable using existing medical tools. Safe and effective vaccines exist for both human papillomavirus and hepatitis B, and targeted antibiotic regimens can successfully clear bacterial stomach infections. However, persistent financial, political, and health-system barriers continue to limit widespread access to these interventions in resource-limited regions.
Nations Implement Screening and Vaccination Programs to Reduce Cancer
Different nations have adopted varied approaches to managing infection-related risks. In countries like Japan, China, and South Korea, high rates of gastric cancer have prompted population-based endoscopic screening programs to detect and treat H. pylori.
Public health guidelines from the World Health Organization and Australian health authorities set a target to vaccinate 90 percent of 15-year-old girls against HPV by 2030 to ensure community-wide protection.
According to Gary Clifford, a senior author and epidemiologist at the International Agency for Research on Cancer, it is an awareness-raising issue and that intervention is possible before the condition progresses toward cancer, provided there is the necessary public buy-in, communication, finance, and political support to implement programs.
Clinical experts advise that individuals experiencing persistent symptoms, significant abdominal discomfort, or gastrointestinal issues should consult qualified medical professionals to discuss appropriate testing, screening options, and preventative strategies.