Objective Colorectal cancer screening by means of faecal immunochemical tests (FITs) requires successive screening rounds for an optimal preventive effect. However, data on the influence of the length of the screening interval on participation and diagnostic yield are lacking. Repeated FIT screening was therefore performed in a population-based trial comparing various repeat intervals.
Design 7501 Dutch individuals aged 50–74 years were randomly selected and invited for two 1-sample FIT screening rounds (haemoglobin (Hb) concentration ≥50 ng/ml, corresponding to 10 μg Hb/g faeces) with intervals of 1 (group I), 2 (group II) or 3 years (group III).
Results In group I, participation was 64.7% in the first screening round and 63.2% in the second. The corresponding percentages for groups II and III were 61.0% vs 62.5% and 62.0% vs 64.0%. Triennial screening resulted in a higher participation rate in the second screening round compared with annual screening (p=0.04). The overall positivity rate in the second screening round was significantly lower compared with the first round (6.0% vs 8.4%; OR 0.69, 95% CI 0.58 to 0.82) and did not depend on interval length (p=0.23). Similarly, the overall detection rate of advanced neoplasia was significantly lower in the second round compared with the first screening round (1.9% vs 3.3%; OR 0.57, 95% CI 0.43 to 0.76) and also did not depend on interval length (p=0.62). The positive predictive value of the FIT did not significantly change over time (41% vs 33%; p=0.07).
Conclusion The total number of advanced neoplasia found at repeat FIT screening is not influenced by the interval length within a range of 1–3 years. Furthermore, there is a stable and acceptably high participation in the second screening round. This implies that screening intervals can be tailored to local resources.
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Funding This trial was funded by the Dutch Cancer Society (EMCR 2006-3673), the Dutch Ministry of Health, Health Care Prevention Program-Implementation (ZonMw 63300022 and ZonMw 120720011), Olympus Medical Systems Europe GmbH, Hamburg, Germany, the Jacoba Foundation and Eiken Chemical Co, Tokyo, Japan. The funding sources had no influence on study design, data collection, monitoring, analysis and interpretation of results or the decision to submit the manuscript for publication.
Competing interests None.
Ethics approval The study was approved by the Dutch Ministry of Health (PG/ZP 2.727.071 and PG/ZP 2.823.158). The study letters and information brochures were approved by the Institutional Review Board at the Erasmus University Medical Centre (MEC-2005-264 and MEC-2008-029).
Provenance and peer review Not commissioned; externally peer reviewed.
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