Variation in colorectal cancer treatment and outcomes in Scotland: real world evidence from national linked administrative data

Abstract

Background: Colorectal cancer (CRC) is the third most common type of cancer in Scotland and the second leading cause of cancer death. Despite improvements in CRC survival over time, Scotland lags behind its UK and European counterparts. Linked administrative datasets can provide a real-world representation of current care as a basis for evaluation of new interventions or policies and to understand variation in care and outcomes. In this study, we aim to provide up to date, population level evidence on CRC treatment and survival in Scotland for patients treated with curative or palliative intent as a basis for the understanding of variation, and to provide data to underpin the evaluation of new treatments. Methods: We conducted a retrospective analysis of adults with an incident CRC registered on the Scottish Cancer Registry (ICD-10 codes C18-20) between January 2006 and December 2018. Data on patients with incident CRC was linked to hospital inpatient records allowing description of their demographic, diagnostic and treatment characteristics. For a curative cohort (n = 26,204) Cox-Proportional Hazards regression models were used to assess the factors affecting overall survival (OS) and CRC specific survival (CRCS). Results: Overall, 32,690 (73\%) and 12,184 (27\%) patients had a diagnosis of colon and rectal cancer respectively. Patients with rectal cancer had a higher comorbidity score compared to those with colon cancer (1.17 versus 1.04). Chemotherapy was used in 30\% with rectal cancer and 42\% with colon cancer. Radiotherapy use was 2\% and 39\% respectively. Five year OS (CRCS) within the curative cohort were 71\% (81\%) and 75\% (82\%) for patients with colon and rectal cancer respectively. After accounting for patient and tumour characteristics, the adjusted regression models show that several factors significantly affect all-cause and CRC-specific survival. Conclusions: National linked administrative datasets have the ability to provide real-world representation of the treatments and outcomes for patients with cancer. In a Scottish population of curative patients with CRC, there was significant variation in survival depending on sex and geography.