Common Colorectal Polyps More Likely to Be Malignant

Posted on March 8th, 2009 by

Common Colorectal Polyps More Likely to Be Malignant

A certain common colorectal polyp is much more likely to be malignant than previously thought. Results from this study, conducted at the Veterans Affairs Palo Alto Health Care System, were recently published in the Journal of the American Medical Association.

Colorectal polyps are growths that occur in the lining of the colon or rectum. They can be detected during a colonoscopy. Colorectal polyps are often benign and may not produce symptoms. In some cases, however, they may cause painless rectal bleeding.

An important part of colorectal cancer prevention has been periodic colonoscopy beginning at age 50, with the removal of polyps if necessary. The appearance and size of the polyp can sometimes indicate whether or not the polyp is cancerous. Polyps that are flatter in appearance, known as nonpolypoid polyps, have previously been thought to be less likely to be malignant than those with a more-round appearance (polypoid polyps).

Researchers evaluated 1,819 patients to determine how frequently nonpolypoid polyps were found during routine screening, routine surveillance, and among patients with symptoms, as well as how frequently nonpolypoid polyps were found to be malignant.

  • Nonpolypoid polyps were found in 5.8% of the patients undergoing routine screening.
  • Nonpolypoid polyps were found in 15.4% of the patients under routine surveillance.
  • Nonpolypoid polyps were found in 6% of the patients with symptoms.
  • Overall, nearly 1% of the nonpolypoid polyps were found to be malignant, which was nine times higher than for polypoid lesions, regardless of size.
  • Nonpolypoid polyps that were smaller in size had the highest risk of cancer.

The researchers found these results interesting because previous research had indicated that nonpolypoid polyps were likely to be precancerous but not malignant. Further research is needed to determine if removal of these polyps will help prevent cancer.

Reference: Soetikno, RM, Kaltenbach T., Rouse, RV, et al. Prevalence of nonpolypoid (flat and depressed) colorectal neoplasms in asymptomatic and symptomatic adults. Journal of the American Medical Association. 2008;299:1027-1035.

Related News:

Physicians Influence Rates of Colorectal Screening (02/13/2008)

Virtual Colonoscopy Suggested as Initial Screening for Colorectal Cancer (10/4/2007)

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