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Colorectal Cancer Screening (PDQ®)

Health Professional Version

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.
aThere 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.
Screening Intervention Study Design Internal Validity Consistency Magnitude of Effects External Validity
Fecal Occult Blood Test RCTs Good Good 15%–33% Fair
Sigmoidoscopy Case-control studies,[1] RCTs in progress Fair Fair About 60%–70% for left colon Fair
Digital Rectal Exam Case-control studies Fair Good No effect Poor
Colonoscopy Case-control studies, RCTs in progress Poor Poor About 60%–70% for left colon; uncertain for right colon 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.
Screening Intervention Study Design Internal Validity Consistency Magnitude of Effects on Surrogate Endpoints External Validity
Sigmoidoscopy [2,3] Case-control studies Poor Fair About 45% decrease in detection rate of cancers compared with colonoscopy Poor
FOBT/ Sigmoidoscopy [4,5] Randomized controlled studies Fair Poor No difference in diagnostic yield between sigmoidoscopy + FOBT vs. sigmoidoscopy alone N/A
Barium Enema [6] Ecologic and descriptive studies Fair Poor Barium enema detects about 30%–50% of cancers detected by colonoscopy N/A
Colonoscopy [7,8] Ecologic and descriptive studies Fair Poor 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. N/A
CT Colonography [9-11] Ecologic and descriptive studies Fair Poor CT colonography may have similar sensitivity to colonoscopy in certain centers Poor
Stool DNA Mutation Tests [12] Studies in progress Unknown Unknown Unknown Unknown
Immunochemical FOBT Cross-sectional study in which iFOBT is administered to persons receiving colonoscopy Good Good iFOBT detects >60% and ≤90% of CRCs N/A


  1. 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. [PUBMED Abstract]
  2. 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]
  3. 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]
  4. 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]
  5. 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]
  6. 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]
  7. 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]
  8. 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]
  9. 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]
  10. 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]
  11. Mulhall BP, Veerappan GR, Jackson JL: Meta-analysis: computed tomographic colonography. Ann Intern Med 142 (8): 635-50, 2005. [PUBMED Abstract]
  12. 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]
  • Updated: February 9, 2015