Colonoscopy Achieves Right-Sided Protection

New evidence bolsters the argument that colonoscopy can effectively prevent proximal colon cancers.

Prior data from Canada suggest that colonoscopy does not reduce right proximal colon cancer incidence and mortality (JW Gastroenterol Feb 20 2009). To investigate this issue further, researchers in Germany conducted a population-based, case-control study involving 1688 patients ≥30 with a first diagnosis of invasive primary colorectal cancer (CRC) and 1932 controls randomly selected from population registries. The aim was to assess whether undergoing colonoscopy during the preceding 10 years reduced the risk for CRC.

The overall exposure to colonoscopy was 41.1% for controls and 13.6% for case patients. Overall, receiving a colonoscopy during the previous 10 years was associated with a 77% lower risk for CRC. Colonoscopy was associated with an 84% lower risk for CRC in the left colon and a 56% lower risk in the right colon. Reduced CRC risk was observed for all stages of cancer and in patients who had undergone colonoscopy for screening or other indications.

Comment: Recent data from Canada suggest that right colon protection is achieved by colonoscopy when performed by gastroenterologists and by endoscopists with high polypectomy and cecal intubation rates (Gastroenterology 2011; 140:65). A previous case-control trial from the same German group that conducted the current study also reported a reduction in right-sided colon cancer after colonoscopy (Gut 2006; 55:1145). The differences in the magnitude of reduced risk findings between these studies might reflect that colonoscopy is performed primarily by gastroenterologists in Germany and primarily by primary care physicians and surgeons in Canada. Indeed, every study that has examined the issue has found better protection against cancer when colonoscopy is performed by gastroenterologists compared with other practitioners. Given that substantial variability also exists in performance by gastroenterologists, these results are a strong endorsement of the current move toward quality measurements in colonoscopy. The best validated quality measurements with regard to protection against cancer are the adenoma detection rate and the cecal intubation rate.

Douglas K. Rex, MD

Published in Journal Watch Gastroenterology February 4, 2011

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