My WebMD Sign In

Please enter email address

Enter your password

Keep me signed in on this computer

Show more Information

If you select "Keep me signed in on this computer", every time you visit WebMD.com you won't have to type your email address and password. This means that a cookie will stay on your computer even when you exit or close your browser which may reduce your levels of privacy and security. You should never select this option if you're using a publicly accessible computer, or if you're sharing a computer with others. Even if you select this option there are some features of our site that still require you to log in for privacy reasons.

Forget your password? Having trouble signing in?

Why should I
sign up for WebMD?

With a WebMD Account you can:

Track your way to weight loss success
Manage your family's vaccinations
Join the conversation

See more benefits Sign Up

Why WebMD?

My WebMD

Show Menu

Facebook Twitter Pinterest

Email a Friend

Print Article

WebMD Home

Cancer Health Center

Colorectal Cancer Health Center

Colorectal Cancer Related Topics

Colorectal Cancer Health Center

Tools & Resources

Font Size

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

RCT = randomized controlled trial.
^a There are no data on the effect of other screening interventions (i.e., fecal occult blood test combined with sigmoidoscopy, barium enema, colonoscopy, computed tomographic colonography, and stool DNA mutation tests) on mortality from colorectal cancer.
�	Fecal Occult Blood Test	Sigmoidoscopy	Digital Rectal Exam	Colonoscopy
Study Design	RCTs	Case-control studies [1], RCTs in progress	Case-control studies	Case-control studies, RCTs in progress
Internal Validity	Good	Fair	Fair	Poor
Consistency	Good	Fair	Good	Poor
Magnitude of Effects	15%-33%	About 60%-70% for left colon	No effect	About 60%-70% for left colon; uncertain for right colon
External Validity	Fair	Fair	Poor	Fair

Table 2. Effect of Screening Intervention on Surrogate Endpoints (e.g., Stage at Diagnosis and Adenoma Detection)

CRC = colorectal cancer; CT = computed tomography; FOBT = fecal occult blood test; iFOBT = immunochemical fecal occult blood test; N/A = not available.
�	Sigmoidoscopy [2,3]	FOBT/ Sigmoidoscopy [4,5]	Barium Enema [6]	Colonoscopy [7,8]	CT Colonography [9,10,11]	Stool DNA Mutation Tests [12]	Immunochemical FOBT
Study Design	Case-control studies	Randomized controlled studies	Ecologic and descriptive studies	Ecologic and descriptive studies	Ecologic and descriptive studies	Studies in progress	Cross-sectional study in which iFOBT is administered to persons receiving colonoscopy
Internal Validity	Poor	Fair	Fair	Fair	Fair	Unknown	Good
Consistency	Fair	Poor	Poor	Poor	Poor	Unknown	Good
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	iFOBT detects >60% and ?90% of CRCs
External Validity	Poor	N/A	N/A	N/A	Poor	Unknown	N/A

References:

Thiis-Evensen E, Hoff GS, Sauar J, et al.: Population-based surveillance by colonoscopy: effect on the incidence of colorectal cancer. Telemark Polyp Study I. Scand J Gastroenterol 34 (4): 414-20, 1999.
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.
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.
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.
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.
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.
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.
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.
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.
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.
Mulhall BP, Veerappan GR, Jackson JL: Meta-analysis: computed tomographic colonography. Ann Intern Med 142 (8): 635-50, 2005.
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.

1 | 2

Next Page >

WebMD Public Information from the National Cancer Institute

Last Updated: May 16, 2012

This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.