Safety of first surveillance colonoscopy at 12 months after piecemeal EMR of large nonpedunculated colorectal lesions.

Background And Aims: After piecemeal EMR (pEMR) of nonpedunculated colorectal lesions ≥20 mm, guidelines recommend first endoscopic surveillance at 6 months. However, initial surveillance at 12 months may be adequate for selected low-risk lesions and could save the cost, risk, and inconvenience of 1 surveillance examination.

Methods: This study retrospectively examined a prospectively collected database of all colorectal lesions referred to our center for endoscopic resection between August 2019 and April 2023. We report recurrence rates of patients with colorectal lesions ≥20 mm removed by pEMR who were assigned to 6-month first surveillance or to 12-month first surveillance (or assigned to a 6-month surveillance visit but did not return until after 10 months).

Results: There were 561 nonpedunculated lesions ≥20 mm that underwent first follow-up, including 490 lesions in 443 patients assigned to 6-month surveillance and 71 lesions in 65 patients assigned to 12-month surveillance. Lesions assigned to 12-month surveillance were smaller (mean size, 25.9 ± 6.1 mm vs 37.0 ± 17.4 mm), more likely serrated (63.4% vs 9.6%), and more often removed by cold pEMR (74.6% vs 20.4%). Twenty-nine lesions in 24 patients assigned to 6-month surveillance presented after 10 months, and their recurrence data were included in the group assigned to 12-month surveillance. Overall recurrence rates at 6 months and 12 months were 10.0% (46 of 461) and 10.0% (10 of 100), respectively. Mean recurrence sizes at 6 and 12 months were 10.9 ± 6.2 mm and 5.0 ± 3.1 mm, respectively. One patient in the 6-month surveillance group had cancer at the pEMR site, but no other recurrences at 6 or 12 months had either cancer or high-grade dysplasia.

Conclusions: Twelve-month surveillance seems acceptable for selected colorectal lesions ≥20 mm removed by pEMR. A randomized trial comparing initial 6-month versus 12-month surveillance is warranted for selected lesions.