Background
Socioeconomic inequalities are among the most important factors explaining variability in cancer mortality within and between European countries. Despite declines in mortality in many settings, the cancer burden remains unequally distributed, with socioeconomic position a key determinant of outcomes across populations. Addressing these inequalities is a central objective of Europe’s Beating Cancer Plan and the European Cancer Inequalities Registry (ECIR). However, the availability of comparable, harmonised information on socioeconomic inequalities in cancer mortality across Europe has been limited by fragmented data sources and substantial geographical and temporal gaps.

Objectives
EU-CanIneq aims to produce data and data intelligence on cancer and cancer inequalities by quantifying and mapping socio-economic inequalities in cancer mortality within and between European countries. The project focuses on the socioeconomic axis, using education as the main indicator, and seeks to provide harmonised, comparable estimates of cancer mortality inequalities to support the ECIR and to inform European cancer policy.

Methods
EU-CanIneq compiles and links high-quality population-based data on cancer mortality, population distribution, and educational attainment for the EU-27, Norway, and Iceland. Education is classified according to the International Standard Classification of Education (ISCED). The core of the project is based on the ERAINHE dataset (complemented by additional information obtained through collaborative work with national experts), which includes observed, harmonised cancer mortality data for 16 Member States derived from linkage of mortality and census data. To fill remaining geographical and temporal gaps, EU-CanIneq developed and applied statistical methods combining ERAINHE data with publicly available sources from the WHO Mortality Database, Eurostat, and the IARC Global Cancer Observatory. Estimates were produced for the period 2015–2019 and are presented as age-standardised mortality rates using the European Standard Population for adults aged 40–79 years.
EU-CanIneq is led by IARC and Erasmus MC, and funded by the European Commission under the EU4Health programme. The project supports the ECIR, whose governance involves DG SANTE, the Joint Research Centre (JRC), the OECD, and IARC.

Results
EU-CanIneq produced estimates of cancer mortality by educational level for all cancers combined and for six major cancer types (lung, colorectum, stomach, breast, cervical, and prostate) for each sex. Country-specific factsheets were developed for 27 Member States plus Norway and Iceland and disseminated through the ECIR. These factsheets provide benchmarking against European averages, comparison with countries in the same geographical area, assessment of inequality gaps, and interpretation of results considering national contexts, including risk factor exposure, healthcare systems, and organisation of cancer care. The project demonstrates substantial variation in socio-economic inequalities in cancer mortality across countries, cancer types, and sexes, consistently to the detriment of people with lower education.

Conclusions
EU-CanIneq strengthens Europe’s capacity to monitor and understand socioeconomic inequalities in cancer mortality by combining observed data with innovative gap-filling, and by delivering harmonised, transparent indicators into the ECIR. The project findings provide robust evidence for identifying priority areas for equity-oriented cancer policies and underline that cancer inequalities affect all populations and that population-level progress in cancer control is not achievable without explicitly tackling socio-economic inequalities across the cancer continuum.