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. Author manuscript; available in PMC: 2015 Nov 20.
Published in final edited form as: N Engl J Med. 2014 Nov 20;371(21):2035. doi: 10.1056/NEJMc1411954#SA1

Long-Term Colorectal-Cancer Mortality after Adenoma Removal

Piet C de Groen 1, Yi-Jhen Li 2, Sudha Xirasagar 3
PMCID: PMC4629486  NIHMSID: NIHMS729491  PMID: 25409379

To the Editor

The study of colorectal-cancer mortality by Løberg et al. (Aug. 28 issue)1 provides no data on the quality of the colonoscopies performed. This limitation outweighs the merits of the large population size and prolonged follow-up in this study, and it precludes meaningful inferences regarding the protective effect of colonoscopy against colorectal cancer. We think the results are best explained by polyps left behind or incompletely removed because of the use of a suboptimal technique.2,3 The timing of colonoscopy may explain the modest mortality benefit among patients with low-risk adenomas versus no benefit among patients with multiple polyps, since younger patients have fewer and less advanced polyps. Our recent study involving patients who received treatment from an endoscopy group with an extraordinary, continuous, and prolonged focus on optimal mucosal inspection and complete polypectomy, as compared with the general population, showed an 83% reduction in the incidence of colorectal cancer and an 89% reduction in mortality.4 The incidence of lung cancer in our study population was identical to that of the general population; this validated the substantial protective effect of high-quality colonoscopy against colorectal cancer. In our opinion, details about the quality of colonoscopy are more important than population size or follow-up in studies of methods to lower colorectal-cancer mortality.5

Acknowledgments

Dr. de Groen reports receiving royalties from a patent and owning potential stock options (in trust at the Mayo Clinic) in EndoMetric, a company that measures the quality of colonoscopies by analyzing streaming videos of endoscopies.

Footnotes

No other potential conflict of interest relevant to this letter was reported.

Contributor Information

Piet C. de Groen, Mayo Clinic, Rochester, MN

Yi-Jhen Li, University of South Carolina, Columbia, SC

Sudha Xirasagar, University of South Carolina, Columbia, SC

References

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