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Colorectal Cancer Screening (PDQ®): Screening - Health Professional Information [NCI] - 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 TestSigmoidoscopyDigital Rectal ExamColonoscopy
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.
Study DesignRCTsCase-control studies[1], RCTs in progressCase-control studiesCase-control studies, RCTs in progress
Internal ValidityGoodFairFairPoor
ConsistencyGoodFairGoodPoor
Magnitude of Effects15%–33%About 60%–70% for left colonNo effectAbout 60%–70% for left colon; uncertain for right colon
External ValidityFairFairPoorFair
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