A Comparison of Risk Classification Systems of Colorectal Adenomas: A Case-Cohort Study

BACKGROUND & AIMS: Because post-polypectomy surveil-lance uses a growing proportion of colonoscopy capacity, more targeted surveillance is warranted. We therefore compared surveillance burden and cancer detection using 3 different adenoma classification systems. METHODS: In a case-cohort study among individuals who had adenomas removed between 1993 and 2007, we included 675 in-dividuals with colorectal cancer (cases) diagnosed a median of 5.6 years after adenoma removal and 906 randomly selected individuals (subcohort). We compared colorectal cancer inci-dence among high-and low-risk individuals defined according to the traditional (high-risk: diameter >10 mm, high-grade dysplasia, villous growth pattern, or 3 or more adenomas), European Society of Gastrointestinal Endoscopy (ESGE) 2020 (high-risk: diameter >10 mm, high-grade dysplasia, or 5 or more adenomas), and novel (high-risk: diameter >20 mm or high-grade dysplasia) classification systems. For the different classification systems, we calculated the number of in-dividuals recommended frequent surveillance colonoscopy and estimated number of delayed cancer diagnoses. RESULTS: Four hundred and thirty individuals with adenomas (52.7%) were high risk based on the traditional classification, 369 (45.2%) were high risk based on the ESGE 2020 classification, and 220 (27.0%) were high risk based on the novel classifica-tion. Using the traditional, ESGE 2020, and novel classifications, the colorectal cancer incidences per 100,000 person-years were 479, 552, and 690 among high-risk individuals, and 123, 124, and 179 among low-risk individuals, respectively. Compared with the traditional classification, the number of individuals who needed frequent surveillance was reduced by 13.9% and 44.2%, respectively, and 1 (3.4%) and 7 (24.1%) cancer diagnoses were delayed using the ESGE 2020 and novel classifications. CONCLUSIONS: Using the ESGE 2020 and novel risk classifica-tions will substantially reduce resources needed for colonoscopy surveillance after adenoma removal.

Automated summary

By comparing three different adenoma classification systems, we found that using the ESGE 2020 and novel risk classifications can substantially reduce resources needed for colonoscopy surveillance after adenoma removal.