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Young G.P.,Flinders University | Symonds E.L.,Flinders University | Allison J.E.,University of California at San Francisco | Allison J.E.,San Francisco General Hospital | And 8 more authors.
Digestive Diseases and Sciences

There is a wide choice of fecal occult blood tests (FOBTs) for colorectal cancer screening. Goal: To highlight the issues applicable when choosing a FOBT, in particular which FOBT is best suited to the range of screening scenarios. Four scenarios characterize the constraints and expectations of screening programs: (1) limited colonoscopy resource with a need to constrain test positivity rate; (2) a priority for maximum colorectal neoplasia detection with little need to constrain colonoscopy workload; (3) an “adequate” endoscopy resource that allows balancing the benefits of detection with the burden of service provision; and (4) a need to maximize participation in screening. Guaiac-based FOBTs (gFOBTs) have significant deficiencies, and fecal immunochemical tests (FITs) for hemoglobin have emerged as better tests. gFOBTs are not sensitive to small bleeds, specificity can be affected by diet or drugs, participant acceptance can be low, laboratory quality control opportunities are limited, and they have a fixed hemoglobin concentration cutoff determining positivity. FITs are analytically more specific, capable of quantitation and hence provide flexibility to adjust cutoff concentration for positivity and the balance between sensitivity and specificity. FITs are clinically more sensitive for cancers and advanced adenomas, and because they are easier to use, acceptance rates are high. Conclusions: FOBT must be chosen carefully to meet the needs of the applicable screening scenario. Quantitative FIT can be adjusted to suit Scenarios 1, 2 and 3, and for each, they are the test of choice. FITs are superior to gFOBT for Scenario 4 and gFOBT is only suitable for Scenario 1. © 2014, The Author(s). Source

Libby G.,Scottish Bowel Screening Research Unit | Brewster D.H.,NHS National Services Scotland | McClements P.L.,NHS National Services Scotland | Carey F.A.,Ninewells Hospital and Medical School | And 4 more authors.
British Journal of Cancer

Background: Randomised trials show reduced colorectal cancer (CRC) mortality with faecal occult blood testing (FOBT). This outcome is now examined in a routine, population-based, screening programme. Methods: Three biennial rounds of the UK CRC screening pilot were completed in Scotland (2000-2007) before the roll out of a national programme. All residents (50-69 years) in the three pilot Health Boards were invited for screening. They received a FOBT test by post to complete at home and return for analysis. Positive tests were followed up with colonoscopy. Controls, selected from non-pilot Health Boards, were matched by age, gender, and deprivation and assigned the invitation date of matched invitee. Follow-up was from invitation date to 31 December 2009 or date of death if earlier. Results: There were 379 655 people in each group (median age 55.6 years, 51.6% male). Participation was 60.6%. There were 961 (0.25%) CRC deaths in invitees, 1056 (0.28%) in controls, rate ratio (RR) 0.90 (95% confidence interval (CI) 0.83-0.99) overall and 0.73 (95% CI 0.65-0.82) for participants. Non-participants had increased CRC mortality compared with controls, RR 1.21 (95% CI 1.06-1.38). Conclusion: There was a 10% relative reduction in CRC mortality in a routine screening programme, rising to 27% in participants. © 2012 Cancer Research UK All rights reserved. Source

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