title: Colorectal cancer: CT colonography and colonoscopy for detection--systematic review and meta-analysis.
abstract: OBJECTIVE
  To perform a systematic review and meta-analysis of published studies assessing the sensitivity of both computed tomographic (CT) colonography and optical colonoscopy (OC) for colorectal cancer detection.
  
  
  METHODS
  Analysis followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses recommendations. The primary data source was the results of a detailed PubMed search from 1994 to 2009. Diagnostic studies evaluating CT colonography detection of colorectal cancer were assessed by using predefined inclusion and exclusion criteria, in particular requiring both OC and histologic confirmation of disease. Studies that also included a mechanism to assess true-positive versus false-negative diagnoses at OC (eg, segmental unblinding) were used to calculate OC sensitivity. Assessment and data extraction were performed independently by two authors. Potential bias was ascertained by using Quality Assessment of Diagnostic Accuracy Studies guidelines. Specific CT colonography techniques were cataloged. Forest plots of per-patient sensitivity were produced on the basis of random-effect models. Potential bias across primary studies was assessed by using the I(2) statistic. Original study authors were contacted for data clarification when necessary.
  
  
  RESULTS
  Forty-nine studies provided data on 11,151 patients with a cumulative colorectal cancer prevalence of 3.6% (414 cancers). The sensitivity of CT colonography for colorectal cancer was 96.1% (398 of 414; 95% confidence interval [CI]: 93.8%, 97.7%). No heterogeneity (I(2) = 0%) was detected. No cancers were missed at CT colonography when both cathartic and tagging agents were combined in the bowel preparation. The sensitivity of OC for colorectal cancer, derived from a subset of 25 studies including 9223 patients, was 94.7% (178 of 188; 95% CI: 90.4%, 97.2%). A moderate degree of heterogeneity (I(2) = 50%) was present.
  
  
  CONCLUSIONS
  CT colonography is highly sensitive for colorectal cancer, especially when both cathartic and tagging agents are combined in the bowel preparation. Given the relatively low prevalence of colorectal cancer, primary CT colonography may be more suitable than OC for initial investigation of suspected colorectal cancer, assuming reasonable specificity.
  
  
  BACKGROUND
  http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.11101887/-/DC1.
authors.affiliation: Department of Radiology, University of Wisconsin School of Medicine and Public Health, E3/311 Clinical Science Center, 600 Highland Ave, Madison, WI 53792-3252, USA. ppickhardt2@uwhealth.org
authors.forename: Perry J
authors.initials: PJ
authors.lastname: Pickhardt
authors.forename: Cesare
authors.initials: C
authors.lastname: Hassan
authors.forename: Steve
authors.initials: S
authors.lastname: Halligan
authors.forename: Riccardo
authors.initials: R
authors.lastname: Marmo
mesh_terms: D003111:Colonic Polyps / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000473:pathology; D023881:Colonography, Computed Tomographic; D003113:Colonoscopy; D015179:Colorectal Neoplasms / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000473:pathology; D006801:Humans; D012680:Sensitivity and Specificity