Polyp Risk Stratification Based on Histology

U.S. vs. U.K. Risk Stratification Guidelines

The American College of Physicians recommends classifying patients with 1-2 small (<10 mm) tubular adenomas without high-grade dysplasia as lower-risk 1, 2
The American College of Physicians recommends classifying patients with any adenoma ≥10 mm, or with villous histology or high-grade dysplasia, or 3-10 adenomas as higher-risk 3, 4
The British Society of Gastroenterology recommends classifying patients with two or more premalignant polyps including at least one advanced colorectal polyp as high-risk 5

Polyps ≥10 mm have significantly higher risk of advanced neoplasia, according to the American College of Physicians 1
Having ≥3 adenomas increases risk, with greater risk at ≥5 adenomas, as stated by the American College of Physicians and the British Society of Gastroenterology 1, 5

The American Gastroenterological Association recommends considering poor tumor differentiation, lymphovascular invasion, submucosal invasion depth >1 mm, positive resection margins, and tumor budding as high-risk features for non-pedunculated malignant polyps 6, 7, 8
The American Gastroenterological Association recommends considering poor tumor differentiation, lymphovascular invasion, and tumor within 1 mm of the resection margin as high-risk features for pedunculated malignant polyps 6, 8

Patients with low-risk adenomas have 3.8-4.4% risk of advanced neoplasia at one year, according to the American College of Physicians 1
Patients with higher-risk adenomas have 11.2% risk of advanced neoplasia at one year, according to the American College of Physicians 1
Patients with high-risk adenomas have 18.7% risk of advanced neoplasia at one year, according to the American College of Physicians 1

The American College of Physicians and the British Society of Gastroenterology recommend surveillance at 5-10 years for lower-risk or low-risk patients 2, 5
The American College of Physicians recommends surveillance at 3 years for higher-risk or intermediate-risk patients 2, 3
The American College of Physicians and the British Society of Gastroenterology recommend surveillance at 1 year or <3 years for highest-risk or high-risk patients 2, 3