title: Computed tomographic colonography versus barium enema for diagnosis of colorectal cancer or large polyps in symptomatic patients (SIGGAR): a multicentre randomised trial.
abstract: BACKGROUND
  Barium enema (BE) is widely available for diagnosis of colorectal cancer despite concerns about its accuracy and acceptability. Computed tomographic colonography (CTC) might be a more sensitive and acceptable alternative. We aimed to compare CTC and BE for diagnosis of colorectal cancer or large 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 radiological investigation of the colon. Patients were randomly assigned (2:1) to BE or CTC by computer-generated random numbers, in blocks of six, stratified by trial centre and sex. We analysed the primary outcome-diagnosis of colorectal cancer or large (≥10 mm) polyps-by intention to treat. The trial is an International Standard Randomised Controlled Trial, number 95152621.
  
  
  RESULTS
  3838 patients were randomly assigned to receive either BE (n=2553) or CTC (n=1285). 34 patients withdrew consent, leaving for analysis 2527 assigned to BE and 1277 assigned to CTC. The detection rate of colorectal cancer or large polyps was significantly higher in patients assigned to CTC than in those assigned to BE (93 [7.3%] of 1277 vs 141 [5.6%] of 2527, relative risk 1.31, 95% CI 1.01-1.68; p=0.0390). CTC missed three of 45 colorectal cancers and BE missed 12 of 85. The rate of additional colonic investigation was higher after CTC than after BE (283 [23.5%] of 1206 CTC patients had additional investigation vs 422 [18.3%] of 2300 BE patients; p=0.0003), due mainly to a higher polyp detection rate. Serious adverse events were rare.
  
  
  CONCLUSIONS
  CTC is a more sensitive test than BE. Our results suggest that CTC should be the preferred radiological test for patients with symptoms suggestive of colorectal cancer.
  
  
  BACKGROUND
  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.
authors: University College London, Centre for Medical Imaging, Podium Level 2, 235 Euston Road, London NW1 2BU, UK. s.halligan@ucl.ac.uk
authors: Steve
authors: S
authors: Halligan
authors: Kate
authors: K
authors: Wooldrage
authors: Edward
authors: E
authors: Dadswell
authors: Ines
authors: I
authors: Kralj-Hans
authors: Christian
authors: C
authors: von Wagner
authors: Rob
authors: R
authors: Edwards
authors: Guiqing
authors: G
authors: Yao
authors: Clive
authors: C
authors: Kay
authors: David
authors: D
authors: Burling
authors: Omar
authors: O
authors: Faiz
authors: Julian
authors: J
authors: Teare
authors: Richard J
authors: RJ
authors: Lilford
authors: Dion
authors: D
authors: Morton
authors: Jane
authors: J
authors: Wardle
authors: Wendy
authors: W
authors: Atkin
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001466:Barium Sulfate; D003111:Colonic Polyps / Q000000981:diagnostic imaging*; D023881:Colonography, Computed Tomographic / Q000379:methods*; D015179:Colorectal Neoplasms / Q000000981:diagnostic imaging*; D003287:Contrast Media; D055088:Early Detection of Cancer / Q000379:methods; D004733:Enema / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012017:Referral and Consultation; D012680:Sensitivity and Specificity
chemical_list: D003287:Contrast Media; D001466:Barium Sulfate