Performance of FIT-based colorectal cancer screening in Denmark from 2014 to 2022

BACKGROUND: Faecal immunochemical test (FIT)-based colorectal cancer (CRC) screening was gradually implemented in Denmark from March 2014 to December 2017. From January 2018, the FIT screening became biennial and is offered to all citizens aged 50-74 years. Citizens with a positive FIT (≥20 μg haemoglobin/g faeces), are scheduled for colonoscopy within 14 days. We examined indicators of quality in FIT-based CRC screening over time and compared with European guidelines. Furthermore, the overall CRC incidence and mortality before, during and after the implementation of CRC screening were examined. METHODS: Nation-wide register data on CRC screening in Denmark were used to assess screening performance during prevalence screening (2014-2017) and incidence screening (2018-2022). For both prevalence and incidence screening we compared results with quality indicators from the European guidelines. Aggregated data on CRC incidence and mortality were obtained from surveillance data. RESULTS: During prevalence and incidence screening, participation in CRC screening was 61.7% and 60.5%, the proportion of positive FITs were 6.9% and 4.7%, respectively. The compliance to follow-up colonoscopy was approximately 90%. The adenoma detection rate increased slightly over time, while number of screen-detected CRC decreased over time. The 3-year post-colonoscopy CRC rate fluctuated around 7.1-8.9% and decreased to 6.8% in 2021. A CRC incidence peak was observed after the introduction of screening followed by a decrease, while mortality continued to decline. CONCLUSION: The performance of FIT-based CRC screening in Denmark is within the acceptable levels defined by the European guidelines; however, improvements are needed, particularly an increase in participation.