Colonoscopy Outperforms Sigmoidoscopy for Cancer Screening

Summary and Comment |
May 28, 2014

Colonoscopy Outperforms Sigmoidoscopy for Cancer Screening

  1. Douglas K. Rex, MD

In a retrospective cohort study, the risk for colorectal cancer was 58% lower after negative colonoscopy than after negative sigmoidoscopy.

  1. Douglas K. Rex, MD

The contention that colonoscopy prevents right-sided colorectal cancer is now supported by numerous lines of evidence, although colonoscopy has not been evaluated in randomized, controlled trials.

In the current retrospective cohort study, investigators compared the risk for colorectal cancer in 42,938 patients with negative colonoscopy and 93,359 patients with negative sigmoidoscopy. All examinations were performed for screening.

During 553,543 person-years of follow-up, 241 cases of colorectal cancer were detected. The risk for colorectal cancer after negative screening colonoscopy was 58% lower overall — and 70% lower for proximal colorectal cancer — compared with the risk after negative screening sigmoidoscopy. The risk for distal cancer was reduced by 41% with colonoscopy compared with sigmoidoscopy, but this difference did not reach statistical significance. Non-Hispanic black patients had a higher risk for colorectal cancer after screening compared with non-Hispanic white patients, but only with sigmoidoscopy and not with colonoscopy.


The evidence that colonoscopy prevents proximal colon cancer, although not from randomized, controlled trials, is now extensive and convincing. However, the level of protection in the right colon as not as great as in the left colon, and additional strides in right colon protection are needed.

Editor Disclosures at Time of Publication

  • Disclosures for Douglas K. Rex, MD at time of publication Consultant / Advisory board Given Imaging; Olympus Corporation America; Exact Sciences; Endo Aid Speaker’s bureau Boston Scientific; Braintree Laboratories; Ferring Pharmaceuticals; Olympus America Grant / Research support CDC; Olympus America; Boston Medical Center Editorial boards World Journal of Gastroenterology; The Journal of Clinical Gastroenterology; Techniques in Gastrointestinal Endoscopy; Gastroenterology & Hepatology; Expert Review of Gastroenterology & Hepatology; Medscape Gastroenterology; World Journal of Gastrointestinal Pharmacology and Therapeutics; Annals of Gastroenterology & Hepatology; World Journal of Gastrointestinal Oncology; Comparative Effectiveness Research; Journal of Anesthesia & Clinical Research; Gastroenterology; World Journal of Gastrointestinal Pathophysiology; Gastroenterology Research and Practice; GI & Hepatology News; Gastroenterology Report; Clinical Epidemiology Reviews; JSM Gastroenterology and Hepatology Leadership positions in professional societies American Society for Gastrointestinal Endoscopy (Councilor); US Multi-Society Task Forces (AGA, ACG, ASGE) (Chair)


Reader Comments (1)

ROBERT BARKER Physician, Gastroenterology, Retired

Data regarding differences in life expectancy of those screened with colonoscopies as opposed to sigmoidoscopy, and, in addition, the cost per year of the years gained might be, would be of interest.

Your Comment

(will not be published)

Filtered HTML

  • Allowed HTML tags: <a> <em> <strong> <cite> <blockquote> <code> <ul> <ol> <li> <dl> <dt> <dd>
  • Web page addresses and e-mail addresses turn into links automatically.
  • Lines and paragraphs break automatically.

Plain text

  • No HTML tags allowed.
  • Web page addresses and e-mail addresses turn into links automatically.
  • Lines and paragraphs break automatically.
Do you have any conflict of interest to disclose?
Last load event
Format: 2016-08-28 20:40:58
This question is for testing whether you are a human visitor and to prevent automated spam submissions.

Vertical Tabs

* Required

Reader comments are intended to encourage lively discussion of clinical topics with your peers in the medical community. We ask that you keep your remarks to a reasonable length, and we reserve the right to withhold publication of remarks that do not meet this standard.

PRIVACY: We will not use your email address, submitted for a comment, for any other purpose nor sell, rent, or share your e-mail address with any third parties. Please see our Privacy Policy.