IARC Estimates Infections Were Linked to 1 in 8 New Cancer Cases in 2024

A global analysis from the International Agency for Research on Cancer (IARC) estimates that 2.3 million new cancer cases in 2024—about 12% of all new cases worldwide—were attributable to infections. The estimate is a population-level measure, not a claim that one in eight people with cancer has a currently detectable infection or that an infection can be identified as the sole cause in an individual patient.

The study, published in The Lancet Oncology, updates earlier estimates using 2024 incidence data and newer evidence about infection–cancer links. Its practical message is less about a new treatment than about prevention: vaccination, testing, treatment and screening can reduce some infection-associated cancers, but access to those measures remains uneven.

Five infections account for most of the estimated burden

IARC identified Helicobacter pylori, human papillomavirus (HPV), hepatitis B virus (HBV), Epstein–Barr virus (EBV) and hepatitis C virus (HCV) as the leading contributors. The agency estimates that H. pylori was associated with about 760,000 cases, mainly stomach cancer; HPV with about 750,000, predominantly cervical cancer; HBV with about 360,000, largely liver cancer; EBV with about 260,000, including nasopharyngeal and some stomach cancers and Hodgkin lymphoma; and HCV with about 160,000, mostly liver cancer.

These figures describe estimated worldwide cases in 2024. They should not be read as a ranking of risk for an individual in Canada. The distribution varies by region and reflects infection prevalence, the cancers counted, prevention coverage and access to diagnosis and care. The estimates also do not mean that infection is the only factor involved in any one cancer.

What changed in this analysis

The study incorporates 16 additional infection–cancer links that were not included in earlier global assessments. These include cancer types associated with HIV and Merkel cell polyomavirus, as well as an expanded set of cancers associated with established carcinogenic infections. For example, newer evidence linking EBV with some stomach cancers is reflected in the updated analysis.

Adding associations improves the completeness of a global estimate, but it does not make every association equally common or equally certain. The study draws on cancer incidence estimates and evidence about the fraction attributable to infection. The resulting totals are useful for public-health planning; they are not a diagnostic tool and cannot determine what caused an individual patient’s cancer.

Prevention tools exist, but they are not equally accessible

IARC points to several established approaches: vaccination against HPV and HBV; appropriate testing and treatment for infections such as H. pylori, HBV, HCV and HIV; measures that reduce infection transmission; and cervical cancer screening. Which measure is appropriate depends on the infection, a person’s history and the relevant national or provincial guidance. A global analysis should not be used to recommend population-wide testing where local guidance does not support it.

The prevention gap is not simply a matter of whether an intervention exists. IARC identifies limited vaccine access and uptake, gaps in screening and diagnosis, affordability, social stigma and uneven health-system capacity as continuing barriers. In some settings, political commitment and resources also shape whether people can complete vaccination or obtain timely treatment.

Relevance for Canadian pharmacy teams

The global 12% estimate is not a Canadian prevalence figure. Still, the prevention categories are familiar to Canadian pharmacy practice: supporting vaccine access where authorized, answering questions about HPV and hepatitis vaccination, and directing people to appropriate testing, primary care and screening services. Pharmacists can reinforce that vaccination prevents particular infections and their downstream risks; it does not replace recommended cancer screening or guarantee that cancer will not occur.

For questions about individual eligibility, vaccine schedules, infection testing or follow-up, pharmacy teams should use current Canadian guidance and local scope-of-practice requirements. The study is a useful prompt to examine prevention gaps—not a basis for changing an individual patient’s cancer work-up.

Why the finding matters

The analysis places the burden of infection-associated cancer alongside prevention opportunities that are already established for several major causes. Its contribution is a refreshed global baseline and a more complete set of infection–cancer links. The next step is not to assume the same pattern everywhere, but to identify where proven vaccination, testing, treatment and screening are reaching people—and where avoidable gaps remain.

Primary sources

• Rumgay H et al. Global burden of cancer attributable to infections in 2024: a worldwide incidence analysis. The Lancet Oncology, published online September 28, 2026.
• IARC study announcement (September 29, 2026).
• IARC questions and answers on the methods, estimates and prevention implications.
• IARC Global Cancer Observatory: Cancer Today.