Exploring age inequalities in the management and survival of colorectal cancer patients

Background: Cancer survival in England is poorer than in other comparable countries. Older cancer patients generally have less evidence-based treatment, and poorer survival than younger patients. This is often attributed to the increasing presence of comorbidity with age. Concerns exist, particularly in England, that age-related differences in cancer outcomes arise because of clinical decision-making based on chronological age alone. This study aims to examine the impact of age on having optimal cancer management for colorectal cancer (CRC). Methods: Using population-based cancer registration records of 139,457 CRC patients diagnosed in Denmark, England, Norway and Sweden during 2010-2012, I estimate and compare age standardised stage-specific three-year net survival, and the likelihood of receiving radical surgery by age and stage. Then, focusing on the 99,942 patients diagnosed in England, I quantify how far age-related differences in patient management are mediated by comorbidity and the diagnostic route, using causal mediation. Findings: In comparison with Denmark, Norway and Sweden, CRC patients in England had lower three year net survival. There was an age gradient in the proportion treated at each stage of disease in England, which was not as evident in the other countries. Analyses focusing on patients without evidence of comorbidity in England and Denmark showed a similar trend. In England, the proportion of patients with evidence of receiving a full investigation and surgical treatment decreased with age. The age differential was partly mediated by the diagnostic route, but not by comorbidity. Interpretation: These findings suggest that the CRC survival deficit in England can be attributed partly to under-management of older patients. Complex interactions between biological, attitudinal and contextual factors may be behind these findings. Raising the proportion of patients receiving optimal management to the levels observed in comparable countries would improve CRC outcomes, provided that adequate post-operative and long-term care are also available.