Related Experiment Video
Updated: May 24, 2026
Evaluation of Colorectal Cancer Risk and Prevalence by Stool DNA Integrity Detection
Published on: June 8, 2020
Potential biases in colorectal cancer screening using faecal occult blood test
Dea Grip Riboe1, Tilde Steen Dogan, John Brodersen
1Research Unit and Section of General Practice, Institute of Public Health, University of Copenhagen, Copenhagen, Denmark.
Background:
Colorectal cancer (CRC) is one of the most common types of cancer in European countries and associated with a high mortality rate. A 16% relative risk reduction (RRR) of mortality was found in a meta-analysis based on four randomized controlled trials (RCT) on CRC screening. The aim of this paper was to scrutinize these trials for potential biases and assess their influence on the screening trials.
Methods:
The four RCTs were reviewed based on the principles of 'Critical Appraisal of the Medical Literature'. Principal investigators of the four RCTs were contacted to clarify uncertainties in their study. Data were collected from The Danish Data Archives. Authors of the Cochrane review were contacted.
Results:
Six biases were identified, of which five favour screening. Three of the biases identified were specific to CRC screening: type of diagnostic method, place of surgery and diagnostic delay.
Conclusion:
The 16% RRR in CRC mortality found in the updated Cochrane review's meta-analysis is overestimated.
Related Concept Videos
01:30Serum Laboratory Studies, Stool Test, Breath Test
01:25Assessment of the Rectum and Anus
Rectal Inspection
Begin by inspecting the perianal and anal areas for color, texture, rashes,...
01:22Bias
In statistics, a sampling bias is created when a sample is collected from a population, and some members of the population are not as likely to be chosen as others (remember, each member...
01:29Bias in Epidemiological Studies
01:30Inflammatory Bowel Disease III: Diagnostic Studies and Management I-Nutritional Therapy
Diagnostic studies
A colonoscopy is the definitive screening test, distinguishing ulcerative colitis from other colon diseases with similar symptoms. During a colonoscopy test, inflamed mucosa with exudate ulcerations can be observed, and biopsies are taken to determine the histologic characteristics of the colonic...