[Abstract] Association between area-based socioeconomic status and colorectal cancer mortality in England

Introduction: Colorectal cancer (CRC) remains one of the leading causes of cancer-related mortality worldwide. While advances in screening, early detection, and treatment have significantly improved survival rates, disparities in outcomes persist. Socioeconomic disparities play a crucial role in influencing CRC mortality – affecting access to healthcare, engagement with screening programmes, early diagnosis, treatment adherence, and overall survival. We conducted a population-based retrospective cohort study to examine the association between area-based socioeconomic status and CRC mortality, by age and sex in England for the period 2011-20.

Material and method: Individual-level anonymised CRC mortality data (ICD-10 codes: C18-20) for 151,050 patients were obtained from the Office for National Statistics. Each patient was assigned to one of five area-based socioeconomic groups using the Index of Multiple Deprivation (IMD quintile 1, most deprived; IMD quintile 5, least deprived). Age- and sex-specific mortality rates and age-standardised mortality rates (standardised to the 2013 European Standard Population) were calculated. CRC mortality rates (per 100,000 population) were calculated for each year of death (2011 to 2020) by age, sex and area-based socioeconomic group (IMD quintiles 1-5). Poisson regression models were constructed to examine the differences in CRC mortality rates between the most and least deprived socioeconomic groups/area.

Results: Overall, colorectal cancer patients from the most deprived socioeconomic group/area (IMD quintile 1) experienced 21-28% higher mortality rates than those in the least deprived socioeconomic group/area (IMD quintile 5). This excess risk of mortality in patients from the most deprived socioeconomic group/area was significantly greater (i.e. more than double) for males (29-46%) compared with females (9-20%).

Conclusion: The association between socioeconomic status and CRC mortality is driven by a complex interplay of higher burden of behavioural risk factors (e.g. unhealthy diet, obesity, smoking, physical inactivity), comorbidities (e.g. diabetes) low uptake of CRC screening (43% vs 57%), delayed diagnosis, and disparities in treatment adherence. The excess CRC mortality in males is attributed to relatively high CRC incidence and enhanced burden of these factors compared to females. By understanding these connections and addressing the social determinants of health, it is possible to reduce this disparity in CRC mortality and improve survival rates in all patients, regardless of their gender and socioeconomic status.