Fecal Immunochemical Testing for CRC Screening
Fecal Immunochemical Testing for CRC Screening
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.
Colorectal cancer (CRC) is a major health problem in the Western world which fulfils the conditions for population-based screening. There is considerable evidence that annual to biennial screening of asymptomatic individuals at average risk using a guaiac-based faecal occult blood test (gFOBT) can detect cancers at an early curable stage, which results in a reduction of 15–33% in CRC-related deaths. Based on these results, repeated FOBT screening has been advocated in international guidelines. Recent studies have indicated that faecal immunochemical testing (FIT) is superior to gFOBT screening, both with respect to participation and diagnostic yield. The introduction of FIT-based screening is therefore widely considered and implemented in the USA, Canada and many countries throughout Europe. Unfortunately, a single FIT is insufficient for the detection of all advanced neoplasia (ie, all patients with CRC or an advanced adenoma, usually defined as an adenoma of ≥10 mm, an adenoma with ≥25% villous histology or with high-grade dysplasia) due to a suboptimal sensitivity for such lesions. This necessitates successive screening rounds, which may result in a similar preventive effect as a screening strategy with an invasive highly sensitive test such as colonoscopy. However, there are no data on the comparison of different intervals for FIT screening and their impact on participation and detection of advanced neoplasia, two factors which both highly determine the efficacy of a screening programme.
The aim of this study was therefore to compare the participation and diagnostic yield of repeated FIT testing with screening intervals of various lengths ranging from 1 to 3 years in a population-based CRC screening trial.
Abstract and Introduction
Abstract
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.
Introduction
Colorectal cancer (CRC) is a major health problem in the Western world which fulfils the conditions for population-based screening. There is considerable evidence that annual to biennial screening of asymptomatic individuals at average risk using a guaiac-based faecal occult blood test (gFOBT) can detect cancers at an early curable stage, which results in a reduction of 15–33% in CRC-related deaths. Based on these results, repeated FOBT screening has been advocated in international guidelines. Recent studies have indicated that faecal immunochemical testing (FIT) is superior to gFOBT screening, both with respect to participation and diagnostic yield. The introduction of FIT-based screening is therefore widely considered and implemented in the USA, Canada and many countries throughout Europe. Unfortunately, a single FIT is insufficient for the detection of all advanced neoplasia (ie, all patients with CRC or an advanced adenoma, usually defined as an adenoma of ≥10 mm, an adenoma with ≥25% villous histology or with high-grade dysplasia) due to a suboptimal sensitivity for such lesions. This necessitates successive screening rounds, which may result in a similar preventive effect as a screening strategy with an invasive highly sensitive test such as colonoscopy. However, there are no data on the comparison of different intervals for FIT screening and their impact on participation and detection of advanced neoplasia, two factors which both highly determine the efficacy of a screening programme.
The aim of this study was therefore to compare the participation and diagnostic yield of repeated FIT testing with screening intervals of various lengths ranging from 1 to 3 years in a population-based CRC screening trial.
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