Pathologic Features of Initial Adenomas as Predictors for Metachronous Adenomas of the Rectum
TL;DR: The risk of metachronous adenomas is closely related to the pathology of initial adenomatous polyps, thus allowing identification of a high-risk group of adenoma patients for close surveillance after their initial polypectomy.
Abstract: Background Colorectal cancer is the third most common cancer in the world, arising mostly from pre-existing adenomatous polyps (adenomas) of the large bowel. Patients with colorectal adenomas are at increased risk of colorectal cancer because of a high recurrence rate for adenomas. We followed a cohort of 1490 patients with rectal adenomas to determine whether recurrence might be related to pathologic characteristics of the initial adenomas. Methods The patients were identified in Haining County, China, from 1977 through 1978 by means of examination with a 15-cm rigid sigmoidoscope. They were followed by endoscopic examination at years 2, 4, 6, 11, and 16 after their initial polypectomy. New adenomas in the rectum were identified in 280 patients in these follow-up examinations. Results Statistically significant twofold to threefold elevated risks of metachronous (recurrent) adenomas were observed for patients who had more than two initial adenomas or whose most advanced initial adenoma was more than 1.0 cm in size, was of villous/tubulovillous type, or showed moderate to severe dysplasia. Much stronger associations were observed for advanced metachronous neoplasms, which are defined as cancers or adenomas with severe dysplasia, with multivariate adjusted relative risks (95% confidence interval) of 4.2 (1.8-9.9) for a large initial adenoma (>1.0 cm), 8.1 (4.2-15.6) for villous/tubulovillous architecture, and 14.4 (5.0-41.3) for severe dysplasia. In particular, patients who had a large (>1.0 cm) adenoma with severe dysplasia at baseline had a relative risk of 37 (7.8-174.7) of developing advanced metachronous neoplasms compared with patients who had small adenoma(s) with mild dysplasia. Conclusions The risk of metachronous adenomas is closely related to the pathology of initial adenomas, thus allowing identification of a high-risk group of adenoma patients for close surveillance after their initial polypectomy.
Cites background from "Pathologic Features of Initial Aden..."
...Most of the studies that assessed risk factors for advanced adenomas at surveillance were either randomized controlled trials of surveillance,(25) chemoprevention trials, prospective surveillance studies,(24) or registry-based observational cohort studies of patients returning for surveillance with less structured follow up outside the context of a clinical trial.(7,12,21,30,31,33,35) The most consistent evidence for predicting subsequent advanced adenomas indicates that multiplicity, size, villous histology, and high-grade dysplasia are the important factors at baseline....
...0 cm at baseline.(30) Noshirwani, et al....
...4), respectively, for the development of subsequent advanced neoplasia (rectal cancer or severe dysplasia) in patients with moderate and severe dysplasia at baseline.(30) Lieberman, et al....
...High-grade dysplasia is related to larger adenoma size and villous component at baseline and is an important predictor for subsequent advanced neoplasia in three of the observational cohort studies.(7,24,30) By definition, all adenomas have some level of dysplasia....
...0) for the detection of advanced neoplasms (rectal cancer, or adenoma with severe dysplasia) at follow up.(30) Loeve reported a significant trend for increasing risk of colorectal cancer at surveillance in relationship to increasing villous component or carcinoma in situ compared with tubular histology....
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