Metachronous Adenomas Occur More Often in the Same Segment or a Proximal Segment Than in a Distal Segment
Douglas K. Rex, MD, MASGE, reviewing Rosser R, et al. J Clin Gastroenterol 2022 Aug 30.
It is well-known that some clustering of adenomas occurs in the colorectum. In a single-center study in patients each with a single index adenoma, 61% of metachronous adenomas were in the same or an adjacent segment (colon divided into 9 segments: cecum, ascending, hepatic flexure, transverse, splenic flexure, descending, sigmoid, rectosigmoid junction, and rectum).
Considering the entire colon, metachronous lesions, over 4 rounds of surveillance, were more likely to occur in a segment proximal to the index adenoma (41%) than in the same segment (39%) or a distal segment (20%; P=.006).
COMMENTThe modern colonoscopist should understand many aspects of how neoplasia changes with colon location. For example, the serrated pathway is on a continuum that increases toward the proximal colon. In addition, flat and depressed lesions are skewed toward the right side of the colon, the risk of proximal cancers increases with age, interval cancers are skewed toward the proximal colon, and proximal lesions are an independent predictor of metachronous adenomas. This is only a partial listing. The tendency of metachronous disease to be proximal to index lesions is a useful concept for colonoscopists to keep in mind, though, of course, the entire colon requires detailed inspection during surveillance.
Note to readers: At the time we reviewed this paper, its publisher noted that it was not in final form and that subsequent changes might be made.
CITATION(S)
Rosser R, Corfe BM, Chapple KS. Metachronous colorectal adenomas occur close to the index lesion. J Clin Gastroenterol 2022 Aug 30. (Epub ahead of print) (https://journals.lww.com/jcge/Abstract)
