Decomposing educational inequalities in cancer mortality: The roles of incidence and survival in Belgium, 2004-2013.

[BACKGROUND] Cancer remains a leading cause of death in Belgium. Socioeconomic inequalities in cancer mortality are insufficiently understood, partially due to the interplay of incidence and survival. Understanding whether mortality inequalities are driven by differences in cancer occurrence or post-diagnosis outcomes is essential for targeted interventions.

[METHODS] In this nationwide observational cohort study, we linked full-population data at the individual level from the 2001 Belgian Census with cancer incidence data (2004-2013) and mortality records. Our study population included all adults aged 30-79 years. Educational attainment served as the primary socioeconomic indicator. Inequalities in cancer incidence and mortality were assessed using Poisson regression, mortality inequalities were decomposed into incidence- and survival-driven components. Analyses were stratified by sex and age group (30-49, 50-79).

[RESULTS] Lower-educated individuals generally experienced higher cancer incidence and mortality, consistent with a traditional social gradient, except for melanoma and female breast cancer, which were more frequent among the highly educated. In younger age groups, inequalities in mortality were predominantly incidence-driven, particularly for lung, stomach, and cervical cancer. Instead, for older adults, survival differences became more prominent, notably for colorectal cancer. Lung cancer was a striking outlier, with mortality inequalities almost entirely incidence-driven across all groups.

[CONCLUSIONS] Socioeconomic inequalities in cancer outcomes differ substantially by cancer type, sex, and age. While prevention remains essential, survival disparities highlight the need for improved access to timely diagnosis and high-quality treatment. Decomposing socioeconomic differences in mortality in incidence and survival yields important insights for targeted policy interventions.