Socio-Economic Position, Cancer Incidence and Stage at Diagnosis: A Nationwide Cohort Study in Belgium

SIMPLE SUMMARY: Socio-economic position is associated with cancer incidence, survival, and mortality. However, this relationship differs across cancer types and socio-economic parameters. Linking the 2001 census to the nationwide Belgian Cancer Registry for cancer diagnoses between 2004 and 2013, the aim of our study was to evaluate and characterise the associations between individual socio-economic and -demographic indicators and the risk of being diagnosed with six cancer types at the population level. With cancer stage being a major determinant for prognosis, a second aim of this study was to explore whether socio-economic position is associated with stage availability and distribution. This study, encompassing almost seven million individuals, identified population groups at increased risk of cancer and unknown or advanced stage at diagnosis in Belgium, and it contributes to building a more comprehensive picture of the complex and multifaceted nature of socio-economic position and cancer incidence in Belgium. ABSTRACT: Background: Socio-economic position is associated with cancer incidence, but the direction and magnitude of this relationship differs across cancer types, geographical regions, and socio-economic parameters. In this nationwide cohort study, we evaluated the association between different individual-level socio-economic and -demographic factors, cancer incidence, and stage at diagnosis in Belgium. Methods: The 2001 census was linked to the nationwide Belgian Cancer Registry for cancer diagnoses between 2004 and 2013. Socio-economic parameters included education level, household composition, and housing conditions. Incidence rate ratios were assessed through Poisson regression models. Stage-specific analyses were conducted through logistic regression models. Results: Deprived groups showed higher risks for lung cancer and head and neck cancers, whereas an inverse relation was observed for malignant melanoma and female breast cancer. Typically, associations were more pronounced in men than in women. A lower socio-economic position was associated with reduced chances of being diagnosed with known or early stage at diagnosis; the strongest disparities were found for male lung cancer and female breast cancer. Conclusions: This study identified population groups at increased risk of cancer and unknown or advanced stage at diagnosis in Belgium. Further investigation is needed to build a comprehensive picture of socio-economic inequality in cancer incidence.