Colorectal cancer is the third most common cancer and the fifth leading cause of cancer death in men worldwide. The majority of colorectal cancers arise from adenomatous polyps, which can be detected with screening colonoscopy. Previously, the investigators of the National Polyp Study (NPS), found that colorectal cancer can be prevented by colonoscopic removal of adenomatous polyps. However, it has been unclear if the cancers prevented were those that had the potential to cause death. Recently, Zauber and colleagues reported* the effect of colonoscopic polypectomy on mortality from colorectal cancer. The researchers conducted a long-term prospective study of the NPS cohort of patients to determine the mortality among patients with adenomas removed compared with the expected mortality from colorectal cancer in the general population. The death rate of patients with adenomas was also compared with an internal control group of patients with nonadenomatous polyps. Among 2,602 patients who had adenomas removed, 12 died from colorectal cancer over a median period 15.8 years, compared with 25 expected deaths in the general population, suggesting a 53% reduction in mortality. Mortality from colorectal cancer among patients with adenomatous polyps was similar to those with nonadenomatous during the first 10 years after polypectomy. Thereafter, mortality increased for patients with adenomas, when strict surveillance was not organized by the study’s investigators. The researchers concede several limitations of the study. A small number of skilled endoscopists performed the colonoscopies, thus the observations may not be applicable to a community practice, for which the reported rates of colorectal cancer after polypectomy are higher than those reported in the NPS. The results of the study may not be representative of the general population, since the study was not a randomized, controlled trial. In conclusion, the study’s findings further support the belief that colonoscopic removal of adenomatous polyps prevents colorectal cancer death. The results also underscore the importance of longterm-term surveillance for patients after the initial removal of adenomatous polyps. More randomized, population-based trials are necessary to determine the effectiveness of screening colonoscopy on colorectal cancer mortality.
Reference: Zauber AG, et al. Colonoscopic Polypectomy and Long-Term Prevention of Colorectal-Cancer Deaths. N Engl J Med 2012;366:687-96.
Bretthauer M, Kalager M. Colonoscopy as a triage screening test. N Engl J Med 2012;366:759-60.