Diminutive Polyps With Advanced Histologic Features Do Not Increase Risk for Metachronous Advanced Colon Neoplasia

BACKGROUND & AIMS: With advances in endoscopic imaging, it is possible to differentiate adenomatous from hyperplastic diminutive (1-5 mm) polyps during endoscopy. With the optical Resect-and-Discard strategy, these polyps are then removed and discarded without histopathology assessment. However, failure to recognize adenomas (vs hyperplastic polyps), or discarding a polyp with advanced histologic features, could result in a patient being considered at low risk for metachronous advanced neoplasia, resulting in an inappropriately long surveillance interval. We collected data from international cohorts of patients undergoing colonoscopy to determine what proportion of patients are high risk because of diminutive polyps advanced histologic features and their risk for metachronous advanced neoplasia.

METHODS: We collected data from 12 cohorts (in the United States or Europe) of patients undergoing colonoscopy after a positive result from a fecal immunochemical test (FIT cohort, n = 34,221) or undergoing colonoscopies for screening, surveillance, or evaluation of symptoms (colonoscopy cohort, n = 30,123). Patients at high risk for metachronous advanced neoplasia were defined as patients with polyps that had advanced histologic features (cancer, high-grade dysplasia, ≥25% villous features), 3 or more diminutive or small (6-9 mm) nonadvanced adenomas, or an adenoma or sessile serrated lesion ≥10 mm. Using an inverse variance random effects model, we calculated the proportion of diminutive polyps with advanced histologic features; the proportion of patients classified as high risk because their diminutive polyps had advanced histologic features; and the risk of these patients for metachronous advanced neoplasia.

RESULTS: In 51,510 diminutive polyps, advanced histologic features were observed in 7.1% of polyps from the FIT cohort and 1.5% polyps from the colonoscopy cohort (P = .044); however, this difference in prevalence did not produce a significant difference in the proportions of patients assigned to high-risk status (0.8% of patients in the FIT cohort and 0.4% of patients in the colonoscopy cohort) (P = .25). The proportions of high-risk patients because of diminutive polyps with advanced histologic features who were found to have metachronous advanced neoplasia (17.6%) did not differ significantly from the proportion of low-risk patients with metachronous advanced neoplasia (14.6%) (relative risk for high-risk categorization, 1.13; 95% confidence interval 0.79-1.61).

CONCLUSION: In a pooled analysis of data from 12 international cohorts of patients undergoing colonoscopy for screening, surveillance, or evaluation of symptoms, we found that diminutive polyps with advanced histologic features do not increase risk for metachronous advanced neoplasia.