Risk of Advanced Colorectal Neoplasia among Patients Undergoing Repeated Colonoscopy Surveillance: A Two-Center Study

Postpolypectomy surveillance plays an important role in the prevention of colorectal cancer. However, optimal surveillance intervals for individuals with multiple prior colonoscopies remain unclear. This study aimed to evaluate the association between prior colonoscopy frequency and advanced neoplasia detection rate (ANDR) according to cumulative colorectal neoplasia treatment history using real-world data from individuals with multiple prior colonoscopies.

This two-center retrospective study analyzed colonoscopies performed between 2010 and 2020 in patients aged ≥40 years. The number of colonoscopies performed within the preceding five years was routinely recorded for each examination. The primary outcome was ANDR. Surveillance intervals were considered appropriate when the ANDR was ≤7%. Analyses were stratified according to cumulative prior lesion history as follows: none, adenoma, advanced adenoma, intramucosal carcinoma, or invasive carcinoma.

Among 22,066 colonoscopies, ANDR was 17.4% at first-ever examination and progressively decreased with increasing recent colonoscopy frequency: 7.2% with no colonoscopy within five years, 3.9% after one, 3.4% after two, and 2.3% after three or more examinations. ANDR remained ≤7% in patients without lesions or with only non-advanced adenomas within an interval of five years or longer before the index colonoscopy. In contrast, ANDR exceeded 7% at intervals of five years or longer in patients with advanced adenoma or intramucosal carcinoma, whereas patients with invasive carcinoma showed persistently high detection rates even at shorter intervals.

Low-risk patients showed a persistently low ANDR, whereas closer surveillance may be justified for patients with advanced adenoma, intramucosal carcinoma, or invasive carcinoma.