Robert H. Fletcher, MD, MSc
What are the diagnostic accuracies and harms of screening tests for colorectal cancer?
Included studies evaluated newer screening tests (computed tomographic colonography [CTC], high-sensitivity fecal occult blood tests [FOBTs], fecal immunochemical tests, and fecal DNA tests) for detecting colorectal cancer in average-risk adults ≥ 40 years of age. Studies of colonoscopy and flexible sigmoidoscopy (FS) done in community settings were included. Exclusion criteria for accuracy studies were case–control design, inadequate use of reference standards, or CTC studies that did not use multidetector scanners or report per-patient data. Outcomes included sensitivity, specificity, and adverse events.
PubMed, Database of Abstracts of Reviews of Effects, Cochrane Database of Systematic Reviews, and Health Technology Assessment databases (all 1999 to 2006); and Web sites of National Guideline Clearinghouse, Institute of Medicine, and National Institute for Health and Clinical Excellence were searched for relevant systematic reviews. MEDLINE and Cochrane Central Register of Controlled Trials (both to Jan 2008) and reference lists were searched for additional primary studies. Experts were contacted. Screening accuracy. 12 studies of colonoscopy or FS, 7 of CTC, and 11 of fecal tests met selection criteria. Harms. 21 studies of colonoscopy or FS and 6 of CTC met selection criteria. Results of selected trials were presented.
Screening accuracy. The Table shows the main results. Pooled data for the 2 largest studies (n = 3764) showed that CTC by certified readers had 92% sensitivity (95% CI 87% to 96%) for detecting adenomas ≥ 10 mm. 3 studies (n = 1781) found that colonoscopy missed 0% to 23% of neoplasia ≥ 10 mm. Harms. 4 CTC studies reported no serious procedure-related harms; 2 reported harms for < 0.1% of CTCs. Pooled data showed that 0.28% (CI 0.15 to 0.52, 12 studies, n = 57 742) of colonoscopies and 0.03% (CI 0.01 to 0.19, 6 studies, n = 126 985) of FSs had serious complications.
Newer stool tests have greater sensitivity than traditional stool tests and similar specificity for colorectal cancer screening. The net impact of colonography remains uncertain.
Diagnostic accuracy of screening tests for colorectal cancer and adenomas*
*FOBT = fecal occult blood test; diagnostic terms defined in Glossary.
†Information provided by author.
Fletcher RH. Review: Newer screening tests have varied sensitivity and moderate-to-high specificity for detecting colorectal cancer. Ann Intern Med. ;150:JC4–15. doi: 10.7326/0003-4819-150-8-200904210-02015
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Published: Ann Intern Med. 2009;150(8):JC4-15.
Colorectal Cancer, Gastroenterology/Hepatology, Gastrointestinal Cancer, Hematology/Oncology, Prevention/Screening.
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Print ISSN: 0003-4819 | Online ISSN: 1539-3704
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