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Fraser CG, Mathew CM, Mowat NA, Wilson JA, Carey FA, Steele RJEvaluation of a card collection-based faecal immunochemical test in screening for colorectal cancer using a two-tier reflex approach. Gut 56: 1415-1418

Scottish Bowel Screening Centre Laboratory, Kings Cross, Dundee DD3 8EA, UK.
Gut (Impact Factor: 13.32). 11/2007; 56(10):1415-8. DOI: 10.1136/gut.2007.119651
Source: PubMed

ABSTRACT The guaiac faecal occult blood test (gFOBT) has been proved as a screening investigation for colorectal cancer, but has disadvantages. Newer faecal immunochemical tests (FITs) have many advantages, but yield higher positivity rates and are expensive. A two-tier reflex follow-up of gFOBT-positive individuals with a FIT before colonoscopy has been advocated as an efficient and effective approach.
A new simple and stable card collection FIT was evaluated.
1124 individuals who were gFOBT positive were asked to provide samples. 558 individuals participated, 320 refused and 246 did not return samples. No evidence of sampling bias was found. 302 individuals tested FIT negative and 256 tested positive. In the 302 FIT-negative individuals, 2 (0.7%) had cancer and 12 (4.0%) had large or multiple (high-risk) adenomatous polyps. In contrast, of 254 positive individuals, 47 (18.5%) had cancer and 54 (21.3%) had high-risk polyps. 93 (30.8%) of the FIT-negative individuals had a normal colonoscopy, but only 34 (13.4%) of the FIT-positive individuals had no pathology. Sensitivity, specificity, and positive and negative likelihood ratios (and 95% CIs) for cancer were 95.9% (84.8 to 99.3), 59.2% (54.7 to 63.5), 2.35 (2.08 to 2.65) and 0.07 (0.02 to 0.27), and for cancer and high-risk polyps were 87.8% (80.1 to 92.9), 65.3% (60.6 to 69.7), 2.53 (2.19 to 2.93) and 0.19 (0.11 to 0.31), respectively.
A two-tier reflex screening algorithm, in which gFOBT-positive participants are tested with a FIT, is effective in identifying individuals at high risk of significant colorectal neoplasia. This strategy is transferable across different FIT formats. This approach has been adopted for the Scottish Bowel Screening Programme.

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    • "A different way of managing the challenge of colonoscopy referrals has been adopted in the screening programme in Scotland, where FIT is used for reflex testing following a positive gFOBT. This has reduced the proportion of screened individuals referred for colonoscopy compared with using second-line gFOBT (Fraser et al, 2006, 2007). However, the potential impact of gFOBT with reflex FIT on cancer incidence and mortality does not appear to have been evaluated. "
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    • "It is known that a large fraction of high grade adenomas actually progress into carcinomas. In fact, the sensitivity in detecting these lesions ranges from 20 to 45%, using noninvasive diagnostic tests based on fecal occult blood [2] [9] [17], and only few data are available on molecular tests [3] [6]. The development of a qualitative analysis of long DNA fragments from stool to identify high-risk adenomas would therefore constitute an important step forward in the area of early diagnosis [3] [7] [27]. "
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    • "Other countries that have evaluated immunochemical tests, such as Korea, China, Israel, Australia, and Italy, have generally concluded that these tests perform better than guaiac tests [22,36–42]. The Scottish Bowel Screening Program adopted a two-tiered screening program using an immunochemical test on guaiac-positive patients that seemed to reduce the number of colonoscopies and the overall cost of screening [43]. The Multisociety Task Force on Colorectal Cancer recommends annual screening using a guaiac test with dietary restrictions or an immunochemical test without dietary restrictions [44]. "
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