Background: Infectious pathogens are strong and modifiable causes of cancer. The aim of this study was to improve estimates of the global and regional burden of infection-attributable cancers to inform research priorities and facilitate prevention efforts.

Methods: We used the GLOBOCAN 2018 database of cancer incidence and mortality rates and estimated the attributable fractions and global incidence for specific anatomical cancer sites, subsites, or histological subtypes known to be associated with ten infectious pathogens classified as human carcinogens. We calculated absolute numbers and age-standardised incidence rates (ASIR) of infection-attributable cancers at the country level. Estimates were stratified for sex, age group, and country, and were aggregated according to geographical regions and World Bank income groups.

Findings: We found that, for 2018, an estimated 2·2 million infection-attributable cancer cases were diagnosed worldwide, corresponding to an infection-attributable ASIR of 25·0 cases per 100 000 person-years. Primary causes were Helicobacter pylori (810 000 cases, ASIR 8·7 cases per 100 000 person-years), human papillomavirus (690 000, 8·0), hepatitis B virus (360 000, 4·1) and hepatitis C virus (160 000, 1·7). Infection-attributable ASIR was highest in eastern Asia (37·9 cases per 100 000 person-years) and sub-Saharan Africa (33·1), and lowest in northern Europe (13·6) and western Asia (13·8). China accounted for a third of worldwide cancer cases attributable to infection, driven by high ASIR of H pylori (15·6) and hepatitis B virus (11·7) infection. The cancer burden attributed to human papillomavirus showed the clearest relationship with country income level (from ASIR of 6·9 cases per 100 000 person-years in high-income countries to 16·1 in low-income countries).

Interpretation: Infection-attributable cancer incidence, in addition to the absolute number of cases, allows for refined geographic analyses and identification of populations with a high infection-associated cancer burden. When cancer prevention is largely considered in a non-communicable disease context, there is a crucial need for resources directed towards cancer prevention programmes that target infection, particularly in high-risk populations. Such interventions can markedly reduce the increasing cancer burden and associated mortality.

Funding: International Agency for Research on Cancer.