A recent study conducted in Norway has demonstrated an increased risk of colorectal cancer in patients with large serrated polyps. Additionally, the study suggests that they may be a biomarker of colorectal cancer risk.
A serrated polyp is comprised of abnormalities in the crypts of the serrated glands within the large intestine. With an estimated prevalence between 13-52%, serrated polyps are thought to be precancerous lesions present within the colon. Therefore, the current recommendations are that they be removed to prevent the formation of cancer. According to the authors of a recent study however, there is insufficient data detailing the long-term risk of colorectal cancer in patients with serrated polyps, and therefore little data to support the current guidelines for their removal.
The study was designed to investigate the risk of developing colorectal cancer in individuals who have large serrated polyps. Conducted in Norway, the study consisted of 12 955 patients aged between 50 and 64 years who were screened for polyps, and was the largest follow up study to date of patients with large serrated polyps and colorectal cancer risk.
The results demonstrated that patients with large serrated polyps are at increased risk for developing colorectal cancer. The risk was increased by 3.7% within 10.9 years of follow up, and was found to be 2.5 times greater than in the general population, and 4 times higher for participants who had no polyps identified at the time of screening. The study also found that cancer may not necessarily develop from the serrated polyp itself, but may develop at another area within the colon. The authors also suggest that the current guidelines recommending a 3 year surveillance period should be re-assessed, due to the results of the study that revealed formation of cancer at a longer follow up period of greater than 10 years.
Awareness and detection of serrated polyps is increasing, however it remains a subject of debate as to whether the risks outweigh the benefits when considering removal of serrated polyps. The risks of removal include bleeding and perforation, due to the location of the polyps within the colon. Further study into the biology of the serrated polyps and their association with colorectal cancer will provide more specific guidelines for dealing with serrated polyps. The authors of the current study suggest that the risks outweigh the benefits, and suggest that biopsy may be a safer alternative.
While further study into the clinical progression of serrated polyps seems necessary, there are no clinical trials currently registered that aim to address the biology of serrated polyps or their association with colorectal cancer. Instead, the currently registered clinical trials appear to be focusing on methods of detection.
Holme, Ø, Bretthauer, M, Eide, TJ, Løberg, EM, Grzyb, K, Løberg, M, Kalager, M, Adami, H-O, Kjellevold, Ø, Hoff, G. “Long-term risk of colorectal cancer in individuals with serrated polyps” Gut doi:10.1136/gutjnl-2014-307793
Press Release: “Marker polyps do not cause cancer” Available from: http://www.alphagalileo.org/ViewItem.aspx?ItemId=147516&CultureCode=en Last Accessed Nov 27, 2014.
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Written by Deborah Tallarigo, PhD