Individual- and area-level socioeconomic inequalities in cancer incidence in the working-age population - a cohort study based on German statutory health insurance data, 2015 to 2019.

INTRODUCTION

Cancer is a major public health challenge in Germany with significant socioeconomic inequalities in incidence and mortality. However, there is only limited research on the incidence of diagnosis-specific cancers and related inequalities among socioeconomic groups within the working-age population. This study aims to address this gap by analysing how the incidence of common cancers depends on individual- and area-level socioeconomic characteristics among working-age women and men.  METHODS: Using a prospective cohort design based on anonymised German statutory health insurance data, this study examined a cohort of 2.23 million individuals aged 25-67 years over a five-year period (2015-2019). Individual socioeconomic position was assessed using educational attainment and occupational skill levels, while area-level deprivation was determined using a composite socioeconomic index. Incidence rates were estimated per 100,000 person-years at risk, age-standardised to the 2013 European standard population. Hazard ratios were calculated using multilevel Cox proportional hazards models.

RESULTS

The analysis revealed 50,276 newly diagnosed cancer cases during the study period. Lower education, lower occupational skill levels and higher area-level deprivation were associated with a higher incidence of stomach, lung, colorectal, prostate, breast and cervical cancer, but a lower incidence rate of malignant melanoma of the skin. After mutual adjustment of the socioeconomic indicators, higher hazard ratios of lung cancer were found for men with lower educational (HR = 2.8, 95%CI:2.3-3.5) and occupational skill levels (HR = 2.8, 95%CI:2.3-3.5) and for women with lower education (HR = 2.3, 95%CI:1.7-3.1). Lower occupational skill levels in both sexes (women HR = 0.6, 95%CI:0.5-0.7; men HR = 0.7, 95%CI:0.6-0.9) and lower educational levels in men (HR = 0.7, 95%CI:0.6-0.8) were independently associated with a lower risk of malignant melanoma. For area-level deprivation, we observed a higher risk of stomach (women 1.6, 95%CI:1.2-2.0; men HR = 1.3, 95%CI:1.1-1.6) and lung cancer (women HR = 1.3, 95%CI:1.1-1.5; men HR = 1.5, 95%CI:1.3-1.7) in more deprived areas, even after adjusting for individual-level socioeconomic characteristics. In contrast, a higher risk of skin melanoma was observed in less deprived areas after individual-level socioeconomic adjustments (women and men HR = 0.6, 95%CI:0.5-0.7).

CONCLUSIONS

Our findings suggest that strategies to prevent cancer in the working-age population should take more account of the unequal structural conditions in which people work and live. The study shows that area-level socioeconomic deprivation has explanatory power for unequal cancer risks beyond the individual characteristics of socioeconomic position.