Background
Stomach cancer is one of the leading causes of cancer mortality worldwide. Although mortality has declined markedly over recent decades, substantial global and regional differences persist. In Europe, stomach cancer mortality has decreased continuously since the 1970s, with a pace and pattern that have varied substantially between countries and across population groups. Socioeconomic inequalities are an important determinant of cancer mortality, especially for stomach cancer. Risk factors such as Helicobacter pylori infection, diet, smoking and alcohol use vary across socioeconomic groups, as does access to timely diagnosis and treatment. Evidence on long-term trends in socioeconomic inequalities in stomach cancer mortality remains limited.

Objectives
We conducted a population-based comparative study to describe long-term trends in stomach cancer mortality by educational level and sex, to quantify changes in absolute and relative educational inequalities over time, and to assess cross-national and regional differences in the most recent period.

Methods
We collected and harmonised population-based mortality data from 17 European countries for men and women aged 35–79 years, covering the period 1980–2022. Educational level was classified according to the 2011 International Standard Classification of Education into primary (ISCED 0–2), secondary (ISCED 3–4), and tertiary (ISCED 5–8) education. Individuals with unknown educational level were excluded from the analyses. ASMRs per 100,000 person-years were calculated using the 2013 European Standard Population. Absolute educational inequalities were assessed using rate differences between primary- and tertiary-educated groups, and relative inequalities using rate ratios. Long-term trends were analysed by estimating average annual percent changes (AAPC) in mortality rates using log-linear regression models. Analyses were conducted by country and sex.

Results
Educational inequalities in stomach cancer mortality were observed in every population and for both sexes. In the most recent period (2001–2021, depending on data availability), mortality levels and educational inequalities were lowest in Northern and Western Europe and highest in the Baltic and Central/Eastern Europe. Stomach cancer mortality declined across almost all countries and educational groups over time, although steeper declines were observed in countries starting with higher mortality rates, particularly in Central/Eastern Europe, with differences in the speed of decline between primary- and tertiary-educated groups.
Absolute inequalities generally declined steadily over time in both sexes, particularly in Northern and Western Europe. In contrast, countries in Central and Eastern Europe started with substantially larger absolute inequalities which narrowed over time but remained larger than those observed in Western and Nordic populations. Relative inequalities showed greater heterogeneity: they were modest and largely stable in Western and Northern Europe, but consistently higher and often persistent in Central/Eastern Europe, particularly in the Baltic countries.

Conclusions
Stomach cancer mortality has declined markedly in Europe over the past four decades, but socioeconomic inequalities persist in all countries. Absolute differences have generally decreased, while relative inequalities remain substantial, especially in Baltic and Central and Eastern Europe. These findings indicate that overall improvements in stomach cancer mortality have not been shared equally and highlight the need to address persistent inequalities in prevention, early detection, and access to healthcare.

?Note: The full manuscript includes additional national partners