≥3 Nonadvanced Adenomas are More Common in the Era of Contemporary Colonoscopy and Not Associated With Metachronous Advanced Neoplasia

Introduction: Data from standard definition colonoscopy era demonstrate patients with an advanced adenoma (>= 10 mm, villous features or high-grade dysplasia) or >= 3 nonadvanced adenomas are considered high-risk for metachronous advanced neoplasia (MAN). Low-risk adenoma (LRA) patients are those with 1 to 2, <10 mm tubular adenomas. High definition colonoscopy, split-dose bowel preparation, and attention to adenoma detection enhance diminutive adenoma detection. We compared baseline adenoma characteristics between patients undergoing colonoscopy in a historic cohort (HC) and contemporary cohort (CC) to determine if number of patients with >= 3 nonadvanced adenomas are increased in CC, and if those features are associated with MAN in CC. Materials and Methods: Patients undergoing their first colonoscopy in HC (<2006) and CC (>= 2006) at age 50 and above were identified through natural language processing. Multivariable regression analysis compared baseline adenoma characteristics between HC and CC, and determined the association between baseline characteristics and MAN in CC patients. Results: In total, 255,074 colonoscopies were performed between 1990 and 2015. A total of 9773 colonoscopies performed in the HC and 59,531 in the CC were included. At baseline, CC patients were more likely to have >= 3 nonadvanced adenomas [odds ratio (OR): 2.1, 95% confidence interval (CI): 1.7-2.6]. In 3,377 CC patients undergoing follow-up colonoscopy, the risk of MAN did not differ between patients with LRA versus those with >= 3 nonadvanced adenomas (6.3% vs. 4.6%, OR: 1.4, CI: 0.58-3.5) including 3-4 (6.1%, OR: 1.4, CI: 0.52-3.6) and >= 5 (7.7%, OR: 1.8, CI: 0.23-14.6), although few patients had >= 5 nonadvanced adenomas. Conclusions: Colonoscopy in the contemporary era increases detection of patients with >= 3 nonadvanced adenomas, which do not increase the risk of MAN compared with LRA patients. A similar surveillance to LRA patients should be considered for those patients.

Automated summary

The study compared baseline adenoma characteristics between patients undergoing colonoscopy in a historic versus contemporary cohort and found an increase in the proportion of patients with >= 3 nonadvanced adenomas in the contemporary cohort. However, follow-up colonoscopies showed that these patients did not have a significantly higher risk of metachronous advanced neoplasia compared to low-risk adenoma patients.