Summary of Evidence
Note: Separate PDQ summaries on Colorectal Cancer Prevention; Colon Cancer
Treatment; and Rectal Cancer Treatment are also available.
Based on solid evidence, screening for colorectal cancer (CRC) reduces CRC mortality, but there is little evidence that it reduces all-cause mortality, possibly because of an observed increase in other causes of death.
Table 1. Effect of Screening Intervention on Reducing Mortality from Colorectal Cancera
|
Fecal Occult Blood Test
|
Sigmoidoscopy
|
Digital Rectal Exam
|
aThere are no data on the effect of other screening interventions (i.e., fecal occult blood test (FOBT)/sigmoidoscopy, barium enema, colonoscopy, computed tomographic [CT] colonography, and stool DNA mutation tests) on mortality from colorectal cancer.
|
Study Design
|
Randomized controlled trials |
Case-control studies, randomized controlled trials in progress |
Case-control studies |
Internal Validity
|
Good |
Fair |
Fair |
Consistency
|
Good |
Fair |
Good |
Magnitude of Effects
|
15%–33% |
About 50% for left colon |
No effect |
External Validity
|
Fair |
Poor |
Poor |
Table 2. Effect of Screening Intervention on Surrogate Endpoints (e.g., stage at diagnosis, adenoma detection)
|
Sigmoidoscopy [1,2]
|
FOBT/ Sigmoidoscopy [3,4]
|
Barium Enema [5]
|
Colonoscopy [6,7]
|
CT Colonography [8-10]
|
Stool DNA Mutation Tests [11]
|
CT = computed tomography; FOBT = fecal occult blood test.
|
Study Design
|
Case-control studies |
Randomized controlled studies |
Ecologic and descriptive studies |
Ecologic and descriptive studies |
Ecologic and descriptive studies |
Studies in progress |
Internal Validity
|
Poor |
Fair |
Fair |
Fair |
Fair |
Unknown |
Consistency
|
Fair |
Poor |
Poor |
Poor |
Poor |
Unknown |
Magnitude of Effects on Surrogate Endpoints
|
About 45% decrease in detection rate of cancers compared with colonoscopy |
No difference in diagnostic yield between sigmoidoscopy + FOBT vs. sigmoidoscopy alone |
Barium enema detects about 30%–50% of cancers detected by colonoscopy |
About 3% of patients with no distal adenomas have advanced proximal neoplasia. There is a threefold increase in this rate in patients with distal adenomas. |
CT colonography may have similar sensitivity to colonoscopy in certain centers. |
Unknown |
External Validity
|
Poor |
N/A |
N/A |
N/A |
Poor |
Unknown |
References
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Cotterchio M, Manno M, Klar N, et al.: Colorectal screening is associated with reduced colorectal cancer risk: a case-control study within the population-based Ontario Familial Colorectal Cancer Registry. Cancer Causes Control 16 (7): 865-75, 2005.
[PUBMED Abstract]
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Schoenfeld P, Cash B, Flood A, et al.: Colonoscopic screening of average-risk women for colorectal neoplasia. N Engl J Med 352 (20): 2061-8, 2005.
[PUBMED Abstract]
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Segnan N, Senore C, Andreoni B, et al.: Randomized trial of different screening strategies for colorectal cancer: patient response and detection rates. J Natl Cancer Inst 97 (5): 347-57, 2005.
[PUBMED Abstract]
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Gondal G, Grotmol T, Hofstad B, et al.: The Norwegian Colorectal Cancer Prevention (NORCCAP) screening study: baseline findings and implementations for clinical work-up in age groups 50-64 years. Scand J Gastroenterol 38 (6): 635-42, 2003.
[PUBMED Abstract]
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Winawer SJ, Stewart ET, Zauber AG, et al.: A comparison of colonoscopy and double-contrast barium enema for surveillance after polypectomy. National Polyp Study Work Group. N Engl J Med 342 (24): 1766-72, 2000.
[PUBMED Abstract]
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Lieberman DA, Weiss DG, Bond JH, et al.: Use of colonoscopy to screen asymptomatic adults for colorectal cancer. Veterans Affairs Cooperative Study Group 380. N Engl J Med 343 (3): 162-8, 2000.
[PUBMED Abstract]
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Imperiale TF, Wagner DR, Lin CY, et al.: Risk of advanced proximal neoplasms in asymptomatic adults according to the distal colorectal findings. N Engl J Med 343 (3): 169-74, 2000.
[PUBMED Abstract]
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Pickhardt PJ, Choi JR, Hwang I, et al.: Computed tomographic virtual colonoscopy to screen for colorectal neoplasia in asymptomatic adults. N Engl J Med 349 (23): 2191-200, 2003.
[PUBMED Abstract]
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Cotton PB, Durkalski VL, Pineau BC, et al.: Computed tomographic colonography (virtual colonoscopy): a multicenter comparison with standard colonoscopy for detection of colorectal neoplasia. JAMA 291 (14): 1713-9, 2004.
[PUBMED Abstract]
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Mulhall BP, Veerappan GR, Jackson JL: Meta-analysis: computed tomographic colonography. Ann Intern Med 142 (8): 635-50, 2005.
[PUBMED Abstract]
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Imperiale TF, Ransohoff DF, Itzkowitz SH, et al.: Fecal DNA versus fecal occult blood for colorectal-cancer screening in an average-risk population. N Engl J Med 351 (26): 2704-14, 2004.
[PUBMED Abstract]
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