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Computed tomographic colonography versus colonoscopy for investigation of patients with symptoms suggestive of colorectal cancer (SIGGAR): a multicentre randomised trial

Computed tomographic colonography versus colonoscopy for investigation of patients with symptoms suggestive of colorectal cancer (SIGGAR): a multicentre randomised trial
Computed tomographic colonography versus colonoscopy for investigation of patients with symptoms suggestive of colorectal cancer (SIGGAR): a multicentre randomised trial
BACKGROUND: Colonoscopy is the gold-standard test for investigation of symptoms suggestive of colorectal cancer; computed tomographic colonography (CTC) is an alternative, less invasive test. However, additional investigation after CTC is needed to confirm suspected colonic lesions, and this is an important factor in establishing the feasibility of CTC as an alternative to colonoscopy. We aimed to compare rates of additional colonic investigation after CTC or colonoscopy for detection of colorectal cancer or large (?10 mm) polyps in symptomatic patients in clinical practice.

METHODS: This pragmatic multicentre randomised trial recruited patients with symptoms suggestive of colorectal cancer from 21 UK hospitals. Eligible patients were aged 55 years or older and regarded by their referring clinician as suitable for colonoscopy. Patients were randomly assigned (2:1) to colonoscopy or CTC by computer-generated random numbers, in blocks of six, stratified by trial centre and sex. We analysed the primary outcome-the rate of additional colonic investigation-by intention to treat. The trial is an International Standard Randomised Controlled Trial, number 95152621.

FINDINGS: 1610 patients were randomly assigned to receive either colonoscopy (n=1072) or CTC (n=538). 30 patients withdrew consent, leaving for analysis 1047 assigned to colonoscopy and 533 assigned to CTC. 160 (30.0%) patients in the CTC group had additional colonic investigation compared with 86 (8.2%) in the colonoscopy group (relative risk 3.65, 95% CI 2.87-4.65; p<0.0001). Almost half the referrals after CTC were for small (<10 mm) polyps or clinical uncertainty, with low predictive value for large polyps or cancer. Detection rates of colorectal cancer or large polyps in the trial cohort were 11% for both procedures. CTC missed 1 of 29 colorectal cancers and colonoscopy missed none (of 55). Serious adverse events were rare.

INTERPRETATION: Guidelines are needed to reduce the referral rate after CTC. For most patients, however, CTC provides a similarly sensitive, less invasive alternative to colonoscopy.

FUNDING: NIHR Health Technology Assessment Programme, NIHR Biomedical Research Centres funding scheme, Cancer Research UK, EPSRC Multidisciplinary Assessment of Technology Centre for Healthcare, and NIHR Collaborations for Leadership in Applied Health Research and Care.
0140-6736
1194-1202
Atkin, Wendy
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Dadswell, Edward
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Wooldrage, Kate
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Kralj-Hans, Ines
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von Wagner, Christian
ddadb46d-8ff8-4519-ad5a-4efdf8c01888
Edwards, Rob
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Yao, Guiqing
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Kay, Clive
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Burling, David
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Faiz, Omar
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Teare, Julian
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Lilford, Richard J.
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Morton, Dion
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Wardle, Jane
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Halligan, Steve
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Atkin, Wendy
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Dadswell, Edward
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Wooldrage, Kate
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Kralj-Hans, Ines
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von Wagner, Christian
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Edwards, Rob
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Yao, Guiqing
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Kay, Clive
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Burling, David
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Faiz, Omar
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Teare, Julian
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Lilford, Richard J.
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Morton, Dion
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Wardle, Jane
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Halligan, Steve
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Atkin, Wendy, Dadswell, Edward, Wooldrage, Kate, Kralj-Hans, Ines, von Wagner, Christian, Edwards, Rob, Yao, Guiqing, Kay, Clive, Burling, David, Faiz, Omar, Teare, Julian, Lilford, Richard J., Morton, Dion, Wardle, Jane and Halligan, Steve (2013) Computed tomographic colonography versus colonoscopy for investigation of patients with symptoms suggestive of colorectal cancer (SIGGAR): a multicentre randomised trial. The Lancet, 381 (9873), 1194-1202. (doi:10.1016/S0140-6736(12)62186-2). (PMID:23414650)

Record type: Article

Abstract

BACKGROUND: Colonoscopy is the gold-standard test for investigation of symptoms suggestive of colorectal cancer; computed tomographic colonography (CTC) is an alternative, less invasive test. However, additional investigation after CTC is needed to confirm suspected colonic lesions, and this is an important factor in establishing the feasibility of CTC as an alternative to colonoscopy. We aimed to compare rates of additional colonic investigation after CTC or colonoscopy for detection of colorectal cancer or large (?10 mm) polyps in symptomatic patients in clinical practice.

METHODS: This pragmatic multicentre randomised trial recruited patients with symptoms suggestive of colorectal cancer from 21 UK hospitals. Eligible patients were aged 55 years or older and regarded by their referring clinician as suitable for colonoscopy. Patients were randomly assigned (2:1) to colonoscopy or CTC by computer-generated random numbers, in blocks of six, stratified by trial centre and sex. We analysed the primary outcome-the rate of additional colonic investigation-by intention to treat. The trial is an International Standard Randomised Controlled Trial, number 95152621.

FINDINGS: 1610 patients were randomly assigned to receive either colonoscopy (n=1072) or CTC (n=538). 30 patients withdrew consent, leaving for analysis 1047 assigned to colonoscopy and 533 assigned to CTC. 160 (30.0%) patients in the CTC group had additional colonic investigation compared with 86 (8.2%) in the colonoscopy group (relative risk 3.65, 95% CI 2.87-4.65; p<0.0001). Almost half the referrals after CTC were for small (<10 mm) polyps or clinical uncertainty, with low predictive value for large polyps or cancer. Detection rates of colorectal cancer or large polyps in the trial cohort were 11% for both procedures. CTC missed 1 of 29 colorectal cancers and colonoscopy missed none (of 55). Serious adverse events were rare.

INTERPRETATION: Guidelines are needed to reduce the referral rate after CTC. For most patients, however, CTC provides a similarly sensitive, less invasive alternative to colonoscopy.

FUNDING: NIHR Health Technology Assessment Programme, NIHR Biomedical Research Centres funding scheme, Cancer Research UK, EPSRC Multidisciplinary Assessment of Technology Centre for Healthcare, and NIHR Collaborations for Leadership in Applied Health Research and Care.

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Published date: 14 February 2013
Organisations: Primary Care & Population Sciences

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Local EPrints ID: 351941
URI: https://eprints.soton.ac.uk/id/eprint/351941
ISSN: 0140-6736
PURE UUID: d1e9e1e6-d9c3-4cbd-924b-e13bc4a6c8d1

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Date deposited: 30 Apr 2013 14:02
Last modified: 05 Oct 2018 12:10

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Contributors

Author: Wendy Atkin
Author: Edward Dadswell
Author: Kate Wooldrage
Author: Ines Kralj-Hans
Author: Christian von Wagner
Author: Rob Edwards
Author: Guiqing Yao
Author: Clive Kay
Author: David Burling
Author: Omar Faiz
Author: Julian Teare
Author: Richard J. Lilford
Author: Dion Morton
Author: Jane Wardle
Author: Steve Halligan

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