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About 2.3 million new cancer cases worldwide in 2024—12%, or roughly one in eight—were attributable to infections, according to an International Agency for Research on Cancer (IARC) estimate published online on 28 September 2026. The finding underscores the value of prevention, including vaccines against human papillomavirus (HPV) and hepatitis B virus (HBV), but vaccination is only one part of the response.
What does “one in eight” mean?
The estimate is a population-level share of new cancer cases worldwide in 2024. It does not mean that one in eight people with an infection will develop cancer, nor does it show that infection was the only risk factor in any particular person’s cancer. IARC’s figure is an estimate of cases attributable to infections across populations, not a tool for diagnosing or predicting an individual’s risk.
The 2024 estimate was published in 2026 and draws on cancer-incidence estimates from IARC’s Global Cancer Observatory. IARC says the assessment includes 16 infection–cancer links not considered in previous global estimates, among them cancers associated with HIV and Merkel cell polyomavirus, and a broader range of cancer types associated with EBV, HBV, HCV and KSHV.
Which infections accounted for the most cases?
IARC identified five leading contributors in its 2024 estimate. The case figures below are approximate global estimates attributable to each infection.
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| Infection | Estimated cases in 2024 | Cancers principally linked in IARC’s summary |
|---|---|---|
| Helicobacter pylori (H. pylori) | About 760,000 | Mainly stomach (gastric) cancer |
| Human papillomavirus (HPV) | About 750,000 | Predominantly cervical cancer; also anal, vulvar, vaginal, penile and some head-and-neck cancers |
| Hepatitis B virus (HBV) | About 360,000 | Mainly liver cancer |
| Epstein-Barr virus (EBV) | About 260,000 | Largely nasopharyngeal cancer, as well as some stomach cancers and Hodgkin lymphoma |
| Hepatitis C virus (HCV) | About 160,000 | Mainly liver cancer |
These figures are estimates of cancer cases attributable to infection at the population level. They do not mean every person with one of these infections will develop cancer.
Why the global average does not describe every region
IARC reports that the infection-attributable burden was highest in Eastern Asia, sub-Saharan Africa, Central and Eastern Europe, and South-East Asia. Both the share of cancers linked to infection and the infections contributing most can differ by region. IARC points to variation in infection prevalence, access to prevention and treatment, and wider social and economic conditions.
Rank #2
For that reason, a region’s raw case count alone cannot show how its burden compares with another region: population size and overall cancer incidence also matter. The global one-in-eight estimate is not a country-specific rate or an individual’s personal probability.
How does the 2024 estimate compare with the earlier figure?
The American Cancer Society’s 2024 publication reported an earlier global estimate of about 2.3 million cases, or 12%, based on 2020 data. IARC’s 2026 publication instead estimates the 2024 burden and includes 16 additional infection–cancer links. The similar rounded totals should not be treated as estimates for the same year or as a direct like-for-like comparison.
What prevention measures are available?
Vaccines can prevent some infection–cancer pathways, especially those involving HPV and HBV. IARC’s prevention summary also points to other measures; the appropriate options depend on the infection and the setting.
- Vaccination: HPV and HBV vaccines are established prevention tools for cancers linked to those viruses.
- Testing and treatment: IARC identifies testing and treatment for H. pylori, HBV, HCV and HIV as part of prevention.
- Reducing transmission: Safe injection practices, access to condoms and HIV pre-exposure prophylaxis (PrEP) are among the measures IARC names.
- Cervical screening: Screening is another important measure against cervical cancer; vaccination does not replace it.
IARC says effective prevention options are not currently available for EBV, H. pylori and KSHV, and supports further vaccine research for those infections. That distinction matters: vaccine prevention is available for some pathways, while other infections call for different existing interventions or further research.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.What can limit prevention?
IARC identifies limited access to and uptake of vaccination, screening, diagnosis and treatment as major challenges. It also notes stigma associated with infections such as HPV and HIV, financial constraints, insufficient political commitment and inequitable access to care. A prevention measure’s existence does not ensure that people can obtain or use it.
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