Spatial and social variations in colorectal cancer within England and Wales

Each year in the UK, more than 42,000 cases of colorectal cancer (CRC) are diagnosed and there are over 16,000 deaths. Despite efforts to reduce inequalities in cancer outcomes, disparities have persisted. This thesis investigates spatial and social variations in CRC incidence, survival and mortality in England and Wales.

A range of data sources were used to obtain information about CRC patients: traditional mortality records; data from the Office for National Statistics Longitudinal Study (LS); and the COloRECTal cancer data Repository (CORECT-R), a contemporary database of CRC data.

Standardised CRC mortality rates were calculated by Local Authority (LA) and area deprivation over a 20-year period, and compared to those for all cancers combined. Time-to-event analysis examined associations between individual-level indicators of socio-economic status and CRC incidence and survival in the LS. Small-area data linkage to CORECT-R enabled investigation of associations between local area characteristics and CRC incidence, using a bespoke risk index.

Spatial variation in colorectal cancer mortality was observed, but there was no clear pattern by LA or area deprivation, in contrast to that for all cancers combined. A stronger association was found between individual socio-economic attributes (educational attainment, social class and housing tenure) and both CRC incidence and survival. The CRC risk index revealed greater distance to health services and green space was associated with worse CRC outcomes and surprisingly closer proximity to retail outlets was associated with better CRC outcomes. No associations of the risk index and stage at diagnosis were found.

Understanding spatial and social variations in CRC is important to inform policies and target interventions to reduce inequalities. Access to up-to-date data is essential to monitor current health outcomes, while combining more traditional datasets with novel data offers potential to examine these relationships in more detail.