Colonoscopic removal of adenomatous polyps reduced colorectal cancer deaths

Zauber AG. N Engl J Med. 2012;366:687-696.

Colonoscopic removal of adenomatous polyps reduced the expected death rate by 53% in patients undergoing treatment for colorectal cancer, according to results from a long-term follow-up study of the National Polyp Study cohort.

This analysis included 2,602 patients with adenomas and 773 without adenomas treated at seven US clinical centers from November 1980 to February 1990. Four in five patients with adenomas underwent at least one surveillance colonoscopy.

After a median follow-up of 15.8 years, 1,246 patients with adenomas had died from any cause. Twelve patients died of colorectal cancer compared with the expected 25.4 deaths in the general population (standardized incidence-based mortality ratio=0.47; 95% CI, 0.26-0.80). Researchers said the reduction in mortality for the first 10 years of follow-up was similar to that for 10 or more years of follow-up (51%). Cumulative mortality rate in the adenoma cohort at 20 years was 0.8% compared with an estimated 1.5% in the general population.

Sensitivity analyses showed a reduction in colorectal cancer-mortality from 56% at 2 years and 44% at 5 years. The 51% reduction in mortality for the follow-up period of 10 or more years was not affected by varying the sojourn time.

There was one disease-specific death among patients with non-adenomatous polyps at 7.7 years of follow-up. Observed disease-specific mortality at 10 years was similar between the two groups.

Dale Shepard, MD, PhD
Dale Shepard

At a time when the benefits for other screening tests are being questioned, data supporting colonoscopy to screen for early-stage colon cancer and removal of any adenomas is crucial. The new data from the NPS trial underscore the need for increased awareness for early detection and prevention of colon cancer. This is not a trial that simply shows that screening colonoscopies improve survival; rather, it specifically shows that those patients who have a screening colonoscopy are found to have adenomatous polyps and have them resected enjoy a survival benefit compared with patients who do not have their polyps detected and removed. Therefore, the survival benefit for routine screening with colonoscopy, which includes patients in whom no lesions are found, remains unknown. This is an important distinction to make, since results of this trial are being simplified in some cases to imply that people who have a colonoscopy live longer than those who don’t.

– Dale Shepard, MD, PhD

Associate staff in solid tumor oncology at the Center for Geriatric Medicine

Cleveland Clinic

Disclosure: Dr. Shepard reports no relevant financial disclosures.

Zauber and colleagues conducted long-term follow-up of the National Polyp Study participants, who previously received diagnostic colonoscopy, polypectomy and surveillance. They reported much lower colorectal cancer mortality among the study participants as compared with the expected mortality among the general population. Colonoscopy in this study is not equivalent to screening colonoscopy in the general population; colonoscopy quality was enhanced by the use of gastroenterologists adhering to a study protocol, and subsequent surveillance was provided to most participants. Nonetheless, this study provides support that the removal of adenomas and subsequent surveillance can yield a reduction in colorectal cancer mortality. Further, these participants had adenomas, and may represent a high-risk — as opposed to average risk — group. Thus, the benefit of polypectomy and surveillance among people with adenomas may have been underestimated.

– Corinne E. Joshu, PhD, MPH

Instructor and Martin D. Abeloff, MD, scholar-in-training in cancer prevention

Department of epidemiology

Johns Hopkins Bloomberg School of Public Health

Disclosure: Dr. Joshu reports no relevant financial disclosures.

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