The analysis identified Helicobacter pylori (H. pylori) and human papillomavirus (HPV) as the leading contributors to infection-related cancers, highlighting the importance of vaccination, early detection, screening and effective treatment of infections in reducing the global cancer burden.
The findings also revealed substantial geographical inequalities, with low- and middle-income countries accounting for 77 per cent of all infection-attributable cancer cases. Researchers said the figures underscored the need to expand access to established preventive interventions, particularly in countries where healthcare resources and cancer registry systems remain limited.
The study assessed cancer cases attributable to 12 infectious agents classified as Group 1 carcinogens by the International Agency for Research on Cancer (IARC). These are agents recognised as capable of causing cancer in humans.
Although cancer is frequently associated with ageing, genetic factors and lifestyle exposures, infections also contribute significantly to the disease burden. Many infection-related cancers are potentially preventable through vaccination, infection control, screening and timely medical treatment.
H. pylori and HPV account for the largest shares
The researchers estimated that H. pylori was associated with approximately 760,000 new cancer cases in 2024, while HPV accounted for about 750,000 cases. Each infection was responsible for roughly four per cent of all new cancer cases worldwide.
H. pylori, a bacterium that infects the stomach, was predominantly associated with non-cardia gastric cancer, which accounted for approximately 700,000 attributable cases. The study estimated that the infection was responsible for 85 per cent of cancers of this specific type.
HPV, meanwhile, was overwhelmingly associated with cervical cancer. The researchers attributed approximately 600,000 cases of cervical cancer to the virus, representing virtually all cases of the disease in the study's estimates.
The findings reinforce the importance of prevention strategies targeting these two infections, particularly HPV vaccination and measures to identify and treat H. pylori infections where clinically appropriate.
Other infectious agents also contributed substantially to the global burden.
Hepatitis B virus (HBV) was associated with approximately 360,000 cancer cases, representing two per cent of all new cancers worldwide. Epstein–Barr virus (EBV) accounted for an estimated 260,000 cases, while hepatitis C virus (HCV) was linked to approximately 160,000 cases.
Liver cancer, particularly hepatocellular carcinoma, accounted for most cancers attributable to HBV and HCV. Nasopharyngeal cancer was the principal contributor to the cancer burden associated with EBV.
Together, the findings demonstrate that a substantial proportion of infection-related cancers is concentrated among a relatively small number of infectious agents and cancer types.
Low- and middle-income countries bear the greatest burden
The study highlighted significant inequalities in the distribution of infection-attributable cancers, with low- and middle-income countries accounting for 77 per cent of the estimated global total.
The concentration of cases in these countries points to persistent challenges in accessing preventive healthcare, including vaccination, infection testing, treatment and screening for precancerous conditions.
Although effective interventions already exist for several cancer-causing infections, their availability and uptake vary widely across countries and communities.
The researchers argued that expanding these interventions could help reduce the number of cancers attributable to infectious agents, particularly in settings where the burden is highest.
The analysis found that eastern Asia accounted for 42 per cent of all infection-related cancer cases worldwide, making it the region with the largest absolute burden.
Its age-standardised incidence rate (ASIR) was 31.9 cases per 100,000 person-years, compared with a global average of 22.7 per 100,000 person-years.
H. pylori and HBV were the leading contributors to infection-attributable cancers in eastern Asia.
Other regions also recorded incidence rates above the global average. Sub-Saharan Africa had an ASIR of 28.5 per 100,000 person-years, southeastern Asia recorded 23.1, while central and eastern Europe had a rate of 24.3.
The proportion of all cancers attributable to infections varied across these regions. In sub-Saharan Africa, infections accounted for 25 per cent of all cancer cases, compared with 16 per cent in southeastern Asia and 10 per cent in central and eastern Europe.
Globally, infection-related cancers represented approximately 12 per cent of all new cancer cases.
The figures illustrate how the contribution of infectious agents to cancer differs across populations, reinforcing the importance of tailoring prevention programmes to regional disease patterns.
Regional differences highlight need for targeted prevention
The researchers also identified differences in the distribution of individual infection-related cancers across countries and regions.
EBV-attributable cancers were concentrated in eastern, southeastern and south-central Asia, which collectively accounted for 65 per cent of the estimated burden associated with the virus.
Mongolia recorded ASIRs above its regional averages for HBV, H. pylori, HCV, HPV and EBV. For H. pylori, rates were consistently above the regional average in Japan and South Korea, while China recorded the highest number of HBV-attributable cancer cases globally.
The study also found that, for every infectious agent examined except HPV, age-standardised incidence rates were higher among males than females across all regions.
The researchers said these differences suggested that cancer prevention priorities should reflect the infectious agents and populations most affected in each location.
Age-standardised incidence rates allow comparisons between populations with different age structures by adjusting for differences in the distribution of age groups. They are useful for comparing cancer patterns but do not represent the actual number of cases in a population.
Prevention remains a major opportunity
The findings provide an updated estimate of the global cancer burden attributable to infectious agents and strengthen the case for wider implementation of established prevention strategies.
Among the interventions identified by the researchers were vaccination against HBV and HPV, alongside testing and treatment for H. pylori, HIV, HBV and HCV.
HBV vaccination can help prevent chronic infection and reduce the risk of liver cancer, while HPV vaccination can protect against virus types responsible for cervical and several other cancers.
Testing and treating eligible patients for H. pylori can also reduce the risk of certain gastric cancers. For people living with HIV or viral hepatitis, appropriate testing, treatment and ongoing medical care can help reduce infection-related health complications, although the benefits vary by infection and cancer type.
The researchers also highlighted the importance of improving access to condoms, HIV pre-exposure prophylaxis (PrEP), safe injection practices and screening for precancerous cervical and anal lesions associated with HPV.
These interventions target different routes of infection and disease progression, making a coordinated approach important for reducing the burden across multiple cancer types.
Beyond existing measures, the study called attention to the need for investment in preventive vaccines targeting EBV, H. pylori and Kaposi's sarcoma-associated herpesvirus.
The development of effective vaccines against these agents could expand the range of infection-related cancers that can be prevented before disease develops.
The authors also emphasised the need for cooperation among governments, public health agencies, healthcare providers and international organisations to address the financial, political and societal barriers that restrict access to prevention.
Researchers caution against interpreting estimates as exact totals
The study's findings should be interpreted in light of limitations in the available data.
The researchers relied on the Global Cancer Observatory's GLOBOCAN database, supplemented by cancer registry information from Cancer Incidence in Five Continents and the African Cancer Registry Network.
They also reviewed relevant research published in PubMed between January 1, 2019, and February 19, 2026, to place their estimates within the existing scientific evidence.
However, cancer registry coverage and data quality vary across countries, with important gaps in some regions, particularly Africa. Limited information can affect the accuracy of estimates and make it difficult to compare the cancer burden consistently between populations.
The researchers also noted that the analysis did not report age-specific burdens and generally applied the same population-attributable fractions to males and females because sex-specific estimates were unavailable.
Population-attributable fractions estimate the proportion of cases that can be attributed to a particular risk factor under specified assumptions. They do not mean that every individual case can be conclusively traced to that infection.
The team did not calculate uncertainty intervals because the different data sources and estimation methods made reliable calculations difficult. Consequently, the actual number of infection-related cancer cases could be higher or lower than the reported estimate, particularly in countries with limited registry coverage.
The researchers also cautioned against interpreting the new figures as evidence that infection-related cancers had increased between 2018 and 2024.
An earlier global estimate attributed approximately 2.2 million cancers to infections in 2018. However, the newer analysis used different data sources, updated population-attributable fractions and included 16 additional infection–cancer pairs. These methodological differences prevent a direct assessment of changes in the global burden over time.
A stronger focus on prevention
Despite the limitations, the study highlights the considerable role infectious agents play in cancer incidence worldwide and the opportunities available to reduce that burden.
With approximately 2.3 million new cancer cases attributed to infections in 2024, researchers have emphasised that expanding vaccination, screening, testing and treatment could prevent a meaningful share of future cases.
The findings are particularly relevant for countries where infection-related cancers account for a large proportion of all cancer diagnoses but access to preventive healthcare remains uneven.
For public health authorities, the challenge extends beyond identifying effective interventions to ensuring that they reach the populations most likely to benefit.
Strengthening health systems, improving public awareness, expanding access to affordable preventive services and investing in reliable cancer registration will be important to translating the study's findings into measurable public health gains.
The researchers' central message is that infection-related cancer is not an unavoidable burden. With sustained investment in proven interventions and the development of new preventive tools, a substantial number of future cancer cases linked to infectious agents could be avoided.