Inequalities in colorectal cancer (CRC) staging and outcomes exist across numerous sociodemographic axes. Early-stage CRC diagnosis is important for treatment success and survival. In this study, we investigate inequalities in CRC staging using registry data for 186 713 first-time CRC cancer diagnoses from 2013 to 2019 in England.
We employ the novel Multilevel Analysis of Individual Heterogeneity and Discriminatory Accuracy (MAIHDA) approach to National Cancer Registry data. We investigate inequalities in CRC staging (early vs advanced stage) via a logistic MAIHDA. We examine a range of intersectional inequalities in CRC staging, across different age, ethnicity, gender and area-level deprivation groups.
Just over half of the staged cancers in the sample were diagnosed at advanced stage (62%). Results demonstrate notable inequalities in the risk of advanced CRC staging, with a gap of 17 percentage points between the strata with the lowest and highest predicted probability of advanced stage CRC diagnosis. These inequalities exist between age groups, ethnicity and deprivation level, with no evidence of gender-related inequalities when other variables are controlled. However, unexpectedly, we find these inequalities to be almost entirely additive in nature.
These results suggest substantial inequalities in advanced stage CRC diagnosis exist, but that these are driven largely by universal processes of inequality, rather than disadvantages associated with single intersectional strata beyond an additive layering of disadvantage. Policy tools to encourage prompt screening engagement and symptom awareness campaigns in pre-screening age groups may benefit from considering the groups most disadvantaged by that additive layering.