Abstract
ObjectiveTo investigate the outcomes of biennial guaiac faecal occult blood test (gFOBT) screening after once-only flexible sigmoidoscopy (FS) screening.MethodsBetween 1994 and 1999, as part of the UK FS Screening Trial (UKFSST), adults aged 55–64 were randomly allocated to an intervention group (offered FS screening) or a control group (not contacted). From 2006, a subset of UKFSST participants (20,895/44,041 intervention group; 41,497/87,149 control group) were invited to biennial gFOBT screening by the English Bowel Cancer Screening Programme. We analysed gFOBT uptake, test positivity, yield of colorectal cancer (CRC), and positive predictive value (PPV) for CRC, advanced adenomas (AAs), and advanced colorectal neoplasia (ACN: AA/CRC).ResultsUptake of gFOBT at first invitation was 1.9% lower (65.7% vs. 67.6%, p < 0.01) among intervention versus control group participants. Positivity was 0.4% lower (2.0% vs. 2.4%, p < 0.01) and CRC yield was 0.08% lower (0.19% vs. 0.27%, p = 0.14). PPVs were also lower in the intervention versus control group, at 10.3% vs. 12.3% (p = 0.44) for CRC, 22.7% vs. 31.4% (p < 0.01) for AA, and 33.0% vs. 43.7% (p < 0.01) for ACN. Among those who refused FS (n = 5532), gFOBT uptake at first invitation was 47.7%, CRC yield was 0.25%, and PPV for ACN was 46.2%. Among FS attenders (n = 15,363), uptake was 72.2%, CRC yield was 0.18%, and PPV for ACN was 27.9%.ConclusionsUptake, positivity and PPV of gFOBT screening were reduced following prior offer of FS screening. However, a quarter of FS screened participants receiving a diagnostic examination after positive gFOBT were diagnosed with ACN.
Highlights
In England, a biennial guaiac faecal occult blood test screening programme, the Bowel Cancer Screening Programme (BCSP), began in 2006.1 In addition, roll-out of a programme of once-only flexible sigmoidoscopy (FS) screening at age 55 started in 2013.2Screening for colorectal cancer (CRC), using either FS or the gFOBT, has been demonstrated to reduce CRC cause-specific mortality in randomized controlled trials.[3,4,5,6,7] Colonoscopy, FS, gFOBT, and faecal immunochemical tests (FITs) have all been included in various screening programmes.[8]
We investigated the impact of prior FS on the outcomes of biennial gFOBT screening using data from participants of the UK Flexible Sigmoidoscopy Screening Trial (UKFSST) who were invited to gFOBT screening through the English BCSP
We provide positive predictive value (PPV) and yield of CRC stratified by gender, as well as the stage distribution of CRCs detected at gFOBT screen
Summary
Screening for colorectal cancer (CRC), using either FS or the gFOBT, has been demonstrated to reduce CRC cause-specific mortality in randomized controlled trials.[3,4,5,6,7] Colonoscopy, FS, gFOBT, and faecal immunochemical tests (FITs) have all been included in various screening programmes.[8] Each screening modality has a different profile in terms of cost, sensitivity, specificity, and burden on endoscopy services. FS is more sensitive than gFOBT and FIT for distal advanced colorectal neoplasia (ACN).[9,10,11,12,13,14,15] It is the only screening modality that has been shown to reduce CRC incidence in multiple randomized controlled trials.[16,17] a single FS does not offer complete protection against distal CRC. Achieving high uptake of either FS or gFOBT screening is challenging.[1,18] The effect of adding once-only FS to biennial gFOBT screening in Journal of Medical Screening 26(1)
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