Advanced-stage CRC incidence patterns following the phased implementation of the CRC screening programme in the Netherlands

BACKGROUND AND AIMS: From 2014, the Dutch colorectal cancer (CRC) faecal immunochemical testing-based screening programme was gradually rolled out by birth cohort. We evaluated changes in advanced-stage CRC incidence by timing of invitation to further strengthen the evidence for the effectiveness of CRC screening. METHODS: Data on advanced-stage CRC incidence in the period 2010-2019 by invitation cohort were collected through the Netherlands Cancer Registry. Crude rates of advanced-stage CRC incidence and cumulative advanced-stage CRC incidence were calculated. Observed advanced-stage CRC incidence and cumulative advanced-stage CRC incidence were compared with expected advanced-stage CRC incidence and cumulative advanced-stage CRC incidence by invitation cohort using trend lines extrapolating data prior to the introduction of screening. RESULTS: For the invitation cohort that was first invited for screening in 2014, advanced-stage CRC incidence increased before the introduction of screening from 94.1 to 124.7 per 100,000 individuals in the period 2010-2013. In 2014, the observed increase was higher than in preceding years, to 184.9 per 100,000 individuals. Hereafter, a decrease in incidence was observed to levels below expected incidence based on trends before the introduction of screening. A similar pattern was observed for invitation cohorts in subsequent years, coinciding with the first invitation to the screening programme. In 2019, the observed incidence for all invitation cohorts remained below expected incidence. The cumulative advanced-stage CRC incidence in the 2014-2016 invitation cohorts was significantly lower than the expected cumulative CRC incidence in the period 2010-2019. CONCLUSIONS: In the period 2014-2019, an increase in advanced-stage CRC incidence was observed for all invitation cohorts first invited for screening, followed by a decrease below expected incidence, following the pattern of the phased implementation. The cumulative advanced-stage CRC incidence in invitation cohorts invited for screening multiple times was lower than expected based on trends from the pre-screening era. These findings support a causal relationship between the introduction of the Dutch screening programme and a decrease in advanced-stage CRC incidence.