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Colorectal Cancer Health Center

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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

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.
Screening InterventionStudy DesignInternal ValidityConsistencyMagnitude of EffectsExternal Validity
Fecal Occult Blood TestRCTsGoodGood15%-33%Fair
SigmoidoscopyCase-control studies,[1]RCTs in progressFairFairAbout 60%-70% for left colonFair
Digital Rectal ExamCase-control studiesFairGoodNo effectPoor
ColonoscopyCase-control studies, RCTs in progressPoorPoorAbout 60%-70% for left colon; uncertain for right colonFair
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