Colonoscopy Works!

Summary and Comment |
September 18, 2013

Colonoscopy Works!

  1. Douglas K. Rex, MD

Data from large, prospective cohort studies support the conclusion that colonoscopy reduces colorectal cancer incidence and mortality.

  1. Douglas K. Rex, MD

Recent case-control and colonoscopy studies have consistently identified reductions in colorectal cancer (CRC) incidence and mortality following colonoscopy. Randomized, controlled trials have established a reduction in distal CRC incidence and mortality following sigmoidoscopy. To further examine this issue, researchers analyzed long-term, follow-up data from the Nurses' Health Study and the Health Professionals Follow-up Study.

Results of 22 years of follow-up of 88,902 participants (1,738,396 person-years) are below:

  • CRC incidence: 1815

  • CRC deaths: 474

  • Reductions in incidence associated with polypectomy (43%), negative sigmoidoscopy (40%), and negative colonoscopy (56%)

  • A 27% reduction in proximal cancer incidence associated with negative colonoscopy (but not with sigmoidoscopy)

  • Reductions in CRC mortality after screening sigmoidoscopy (41%) and after screening colonoscopy (68%)

  • A 53% reduction in proximal CRC mortality after screening colonoscopy (but not after sigmoidoscopy)

  • Lasting reductions in CRC incidence after negative colonoscopy (≤3 years, 65%; 3.1 to 5 years, 60%; 5.1 to 10 years, 48%; 10.1 to 15 years, 74%)

  • Lasting reduction in CRC incidence from 5.1 to 15 years after negative colonoscopy for both proximal (40%) and distal CRC (65%)

  • Attenuated reduction in cancer incidence after polypectomy in patients with high-risk adenomas

  • Higher likelihood of CpG island methylator phenotype (odds ratio, 2.19) or microsatellite instability (OR, 2.10) in cancers occurring ≤5 years after colonoscopy


Although these results present nothing new, the large size and prestige of these surveys reinforces previous evidence. Colonoscopy does protect against colorectal cancer incidence and death, but the effect is less in the proximal colon than in the distal colon. The results also augment mounting evidence of sessile serrated polyps in the proximal colon being missed, ineffectively resected, or both. Additional education could improve identification and removal of these lesions.

The results in the polypectomy cohort are disappointing and suggest that endoscopists must do more to effectively identify high-risk patients. Also, perhaps more-aggressive follow-up intervals are needed in highest-risk polyp groups.

Editor Disclosures at Time of Publication

  • Disclosures for Douglas K. Rex, MD at time of publication Consultant / Advisory board Exact Sciences; Ferring Pharmaceuticals; Given Imaging; Olympus Speaker’s bureau Boston Scientific; Braintree; Ferring Pharmaceuticals Grant / research support Battelle; Braintree; Northwestern University; Olympus America Editorial boards Annals of Gastroenterology and Hepatology; Comparative Effectiveness Research; Expert Review of Gastroenterology and Hepatology; Gastroenterology; Gastroenterology and Hepatology News; Gastroenterology Report; Gastroenterology Research and Practice; Journal of Clinical Gastroenterology; Techniques in Gastrointestinal Endoscopy; World Journal of Gastroenterology; World Journal of Gastrointestinal Oncology; World Journal of Gastrointestinal Pathophysiology; World Journal of Gastrointestinal Pharmacology and Therapeutics


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