Abstract

Background: Patients who have had a colorectal adenoma are likely to develop a metachronous adenoma and therefore need to be kept under surveillance. It is essential to avoid unnecessary examinations by tailoring the frequency of follow up examinations to individual risk.

Methods: A total of 3134 patients undergoing endoscopic removal of colorectal adenomas were prospectively recorded on the Erlangen Registry of Colorectal Polyps between 1978 and 1996. A multivariate analysis of 1159 patients on long term follow up was performed to identify risk factors determining surveillance intervals for patients with metachronous adenomas of advanced pathology—that is, adenomas >10 mm or with high grade dysplasia or invasive carcinoma.

Results: Univariate analysis revealed that sex, parental history of colorectal carcinoma, and characteristics of the initial findings—that is, size, multiplicity, and amount of villous structure—were significant predictors of metachronous adenomas of advanced pathology. On the basis of multivariate analysis, two risk groups were identified: (1) patients with no parental history of colorectal carcinoma with only small (≤10 mm) tubular adenomas at the initial clearing examination have a very low risk, and we estimated that 10% will develop advanced metachronous adenomas after 10 years; (2) the high risk group contained all other patients, 10% of whom will show metachronous adenomas of advanced pathology at follow up after only three years.

Conclusions: The risk of developing metachronous adenomas with advanced pathology can be stratified for various patient and adenoma characteristics. Surveillance intervals can be scheduled for low risk (10 years) and high risk (three years) patients. Risk related follow up thus helps to avoid unnecessary examinations.