Colorectal Cancer Screening - National Cancer Institute


Purpose of This PDQ Summary


Summary of Evidence


Significance


Evidence of Benefit


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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 Cancer^a

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	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)

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	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

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]
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]
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]
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]
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]
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]
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]
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]
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]
Mulhall BP, Veerappan GR, Jackson JL: Meta-analysis: computed tomographic colonography. Ann Intern Med 142 (8): 635-50, 2005. [PUBMED Abstract]
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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