Incomplete Colonic Polyp Resection May Increase Risk for Metachronous Neoplasia

colon polyp
colon polyp
A team of researchers sought to determine the rate of metachronous adenoma after incomplete resection of colonic polyps.

Incomplete resection of colonic adenomata may be a significant risk factor for metachronous neoplasia, and the method of removal may contribute to incomplete resection, according to the results of a study published in Gastrointestinal Endoscopy.

Researchers sought to compare the rate of metachronous adenoma that is attributable to incomplete resection in polyps measuring 6 to 9 mm with those measuring 10 to 20 mm. The study authors calculated the segmental metachronous adenoma rate attributable to incomplete resection (SMAR-IR) by subtracting the rate of metachronous neoplasia in segments without adenoma from segments with adenoma.

A total of 337 patients (mean age, 60.5 [9.6 years]; 52.2% women; 56.7% White) were included in the analysis. Within this cohort, 146 patients had a tubular adenoma measuring 10 to 20 mm, and 191 patients had a tubular adenoma measuring 6 to 9 mm as the most advanced lesion.

For participants who underwent resection of an index tubular adenoma measuring 10 to 20 mm, the SMAR in segments with adenoma was 21.0% and in segments without adenoma was 9.6%, which yielded an SMAR-IR of 11.4% (95% CI, 4.5-18.3).

Among those who underwent resection of an index tubular adenoma measuring 6 to 9 mm, the SMAR in segments with adenoma was 22.0% and in segments without adenoma was 8.8%, which resulted in an SMAR-IR of 13.2% (95% CI, 7.2-19.4). The SMAR-IR ranged from 7.0% to 15.5% for polyps measuring 6 to 20 mm among the 6 participating colonoscopists.

“The SMAR-IR for [tubular adenomas] 6 to 9 mm that were removed with cold forceps was higher than those removed…by snare cautery or cold snare (16.5% vs 12.8% vs 10.6%, respectively),” stated the researchers. “Thus, our study shows that the method of removal of small polyps, which predisposes to incomplete resection actually has long term negative consequences in [terms] of metachronous neoplasia.”

The study has several limitations, according to the investigators. The methodology of calculating SMAR-IR does not account for a field defect predisposing to recurrent neoplasia preferentially in the segment of prior resection. In addition, the SMAR-IR relies on the accurate endoscopic identification of polyp segment location; therefore, the rates of SMAR-IR may be affected by identifying the segment and may be underestimated.

“We show that SMAR-IR is a promising metric in monitoring retrospectively polypectomy quality,” the study authors concluded. “The main finding of this study is that the recurrence from incomplete resection appears to occur in 6 to 9 mm lesions at a rate similar to larger lesions among our cohort. The extent to which this can be reduced by resection technique education and monitoring deserves further study.”

Disclosures: One of the authors reported affiliations with medical device and endoscopic imaging companies. Please see the original reference for a full list of disclosures.


Alsayid M, Van J, Ma K, Melson J. Segmental metachronous adenoma rate as a metric for monitoring incomplete resection in a colonoscopy screening program. Gastrointest Endosc. Published online February 6, 2021. doi:10.1016/j.gie.2021.01.046