Background: Colorectal cancer (CRC) has the third-highest age-standardized rate for both incidence and mortality in Europe. CRC risk and outcomes are strongly related to lifestyle factors (i.e., poor diet, inactivity, high alcohol consumption, smoking habits, and high body weight) and low use of healthcare services which are more prevalent in low socioeconomic groups. Despite that, at present, comprehensive data about socioeconomic inequalities in CRC mortality across Europe are limited.
Objectives: The present study aims at assessing trends of socioeconomic inequalities in CRC mortality in Europe using representative population data.
Methods: Population-based mortality data on CRC (ICD9 codes C18-21) by education level and sex were collected and harmonized for 17 European countries, for individuals aged 35–79 years and across different time periods between 1970 and 2022. Age-standardized mortality rates (ASMRs) per 100,000 person-years using the 2013 European Standard Population were calculated and reported by country, period of observation, sex, and educational level. Both absolute and relative inequalities were estimated considering the rates difference and rate ratio between primary and tertiary educated individuals, respectively. To quantify trends, country-specific estimates of the annual percentage changes (AAPC) in mortality rates were estimated by fitting a linear regression model, where the logarithm of the ASMRs was regressed on time. The analysis was restricted to the period 1980-2022 to ensure maximum comparability of data, and educational level was used as indicator of socioeconomic condition. In detail, 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) levels and used as an indicator of socioeconomic condition.
Results: In the period 1980-2022, in almost all countries and in both sexes, ASMRs for CRC were stable or steadily decreased over time across all educational levels. The decrease was less pronounced among primary educated individuals, particularly in countries of the Baltic/Central/East Europe and in men, leading to an increase in educational inequalities over time.
In the most recent period (2001-2022), the magnitude of educational inequalities largely varied across countries. In men, inequalities were higher in countries of the Baltic/Central/East Europe; while among women, inequalities were higher in countries of both the Baltic/Central/East and North Europe.
Absolute educational inequalities remained quite stable over the study period in almost all countries. In contrast, relative inequalities increased in almost all countries for men. Among women, increasing relative inequalities were estimated in some countries of the north and Baltic/Central/East Europe.
Conclusions: Even though CRC mortality generally decreased in Europe over the past decades, substantial educational inequalities still exist, and they have increased over time in most countries. Educational inequalities in CRC are likely to be driven by inequalities in the distribution of risk factors across educational groups and both lower screening participation and access to curative services. Target policies addressing inequalities in CRC mortality are needed as socioeconomic differences exist everywhere in Europe, among and within countries, even in places with a more solid egalitarian system.