Adenoma detection rate and risk of colorectal cancer.

GOALS: The aim of this paper was to discuss association between adenoma detection rate (ADR) and interval colorectal cancer risk.

BACKGROUND: Adenoma detection rate is being used as a benchmark quality measure for colonoscopy. There are three studies showing inverse association between ADR and interval colorectal cancer risk. One recent study reports significant impact of increased ADR on decreasing interval colorectal cancer risk.

STUDY: We discussed evidence for using ADR as a quality measures in colonoscopy and flexible sigmoidoscopy. We revised three studies (Kaminski et al., N Engl J Med 2010; Corley et al., N Engl J Med 2014 and Rogal et al., Clin Gastroenterol Hepatol, 2013) analyzing association between ADR and interval colorectal cancer. We collated strengths and weaknesses of these studies with the perspective of clinical impact of their results.

RESULTS: Kaminski et al. and Corley et al. reported inverse association between ADR at colonoscopy and interval colorectal cancer. Kaminski et al. showed that patients examined by endoscopists with ADR of less than 20% had over 10 times greater risk of interval colorectal cancer during the follow-up time than those examined by endoscopists with ADR ≥20%. Additionally, Corley et al. showed that ADR ≥28% resulted in a significantly lower risk of colorectal cancer death than ADR of less than 19%. In parallel, Rogal et al. reported similar association for flexible sigmoidoscopy, with 2.4 higher odds of interval colorectal cancer diagnosis during follow-up time in patients examined by endoscopists with distal ADR <7.2% than those with distal ADR ≥7.2%. Apart from inevitable clinical importance of the studies, they are not without disadvantages. In Kaminski et al. study cohort and study endpoint are well defined, but there is lack of statistical power to provide more robust results. In Rogal et al. study cohort is well defined, but approximation of the study endpoint was used. Finally, Corley et al. study has both poorly defined study cohort and study endpoint, but has the highest statistical power of all three to detect the differences for both interval colorectal cancer and colorectal cancer death.

CONCLUSION: Both, inverse relationship between ADR and ADR improvement and colorectal cancer risk and death reaffirm ADR as a crucial quality control parameter.