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Colorectal Cancer Screening (PDQ®)
Patient Version   Health Professional Version   Last Modified: 08/26/2008
Table 1. Effect of Screening Intervention on Reducing Mortality from Colorectal Cancera

  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


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