Importance of Surveillance Colonoscopy Questioned

A new study concludes that forgoing surveillance colonoscopy after removal of adenomatous polyps results in colorectal cancer (CC) mortality similar to that of the general population.

Researchers at the University of Oslo (Norway), Telemark Hospital (Skien, Norway), and other institutions analyzed data from the Cancer Registry of Norway, and identified all patients who had polyps removed during 1993-2007. On the basis of pathology reports, 48.8% of patients were classified as high risk, and the remaining 51.3% of the patients were classified as low risk. The primary outcome was CC mortality. The authors noted that surveillance colonoscopy for low-risk adenomas was not recommended in Norway during the study period.

The results showed that during a median follow-up period of 7.7 years, 1,273 of the patients had newly diagnosed CC, with 383 patient deaths from CC. When comparing the expected and observed number of cancers, adenoma removal was associated with a standardized mortality ratio (SMR) of 0.96. Among men, polypectomy conferred 14% reduction in the SMR, while women derived no SMR benefit. An analysis of 20,423 patients who underwent polypectomy prior to 2002 yielded an SMR of 1.10, suggesting no mortality benefit among patients followed for 10 years or longer. The study was published in the August 28, 2014, issue of the New England Journal of Medicine (NEJM).

“Surveillance every five years after removal of low-risk adenomas may confer little benefit over less intensive surveillance strategies,” concluded lead author Magnus Loberg, MD, of the University of Oslo, and colleagues. “Furthermore, complications associated with colonoscopy are not trivial and might offset the benefit of surveillance.”

“Colon-polyp surveillance now accounts for about 25% of colonoscopies among persons over 50 years of age in the United States, a substantial burden on health resources,” commented David Lieberman, MD, of Oregon Health and Science University (OHSU; Portland, USA), in an accompanying editorial. “It is quite possible that the initial colonoscopy and polypectomy reduce the risk of death from colorectal cancer and that surveillance may have little additional effect on mortality.”

The risks and benefits of adenoma surveillance need to be balanced, particularly in patients who have significant comorbidity. The cut off age for stopping surveillance is usually quoted as 75 years, as the remaining life expectancy is likely less than the average time required for new adenomas to become malignant. After this age, it is unlikely that the benefits of surveillance will outweigh the potential risks of the procedure.

Related Links:
University of Oslo
Telemark Hospital