Article

Evaluation of a card collection-based faecal immunochemical test in screening for colorectal cancer using a two-tier reflex approach.

Scottish Bowel Screening Centre Laboratory, Kings Cross, Dundee DD3 8EA, UK.
Gut (impact factor: 10.11). 11/2007; 56(10):1415-8. DOI:10.1136/gut.2007.119651 pp.1415-8
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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Keywords

302 FIT-negative individuals
 
558 individuals
 
colorectal cancer
 
different FIT formats
 
FIT negative
 
FIT-negative individuals
 
FIT-positive individuals
 
gFOBT-positive individuals
 
gFOBT-positive participants
 
guaiac faecal occult blood test
 
high-risk polyps
 
negative likelihood ratios
 
Newer faecal immunochemical tests
 
sampling bias
 
Scottish Bowel Screening Programme
 
significant colorectal neoplasia
 
stable card collection FIT
 
two-tier reflex follow-up
 
two-tier reflex screening algorithm
 
yield higher positivity rates
 

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