Approximately 10% of neoplastic polyps that were 5-20 mm in size were not completely resected in a series of 1,427 patients undergoing colonoscopy, Dr. Heiko Pohl and his colleagues reported in the January issue of Gastroenterology.
Biopsies from the resection margins of 346 neoplastic polyps showed that some neoplastic tissue had been left behind in 35 cases in the Complete Adenoma Resection (CARE) study, which involved 11 experienced gastroenterologists practicing at two large academic medical centers.
Video source: American Gastroenterological Association YouTube channel
The rate of incomplete resections varied widely across the different endoscopists, from 6.5% to 22.7%. Moreover, these physicians were aware that they were participating in the study and may have been more careful than usual to accomplish complete resection.
"Our study provides plausible data that incomplete polyp resection in daily clinical practice is relatively common and may contribute to future interval cancers," said Dr. Pohl of White River Junction (Vt.) VA Medical Center and Dartmouth-Hitchcock Medical Center, Lebanon, N.H., and his associates.
The findings also suggest that quality measures for colonoscopy, which to date have focused primarily on detection rates, should now include the completeness of the resection. "The performance of high-quality and effective colonoscopy not only requires expertise in finding neoplastic polyps, but also removing them," the investigators noted (Gastroenterology 2013;144:74-80).
Until now, there has been "surprisingly little direct information on the adequacy of polyp resection. It is generally assumed that resection is complete if no apparent polyp tissue is visible after resection. Using a snare with electrocautery should further destroy any remaining polyp tissue," but whether it actually does so has never been tested, they said.
Dr. Pohl and his colleagues reviewed the cases of all adults aged 40-85 years who presented for outpatient colonoscopy at the two study centers, had no history of inflammatory bowel disease, had no coagulopathies, and were found to have at least one polyp that was 5-20 mm in size.
The board-certified gastroenterologists participating in the study used standard colonoscopes and polypectomy snares to remove the lesions, along with standard electrocautery equipment. The polyps were measured and resected, then the gastroenterologists inspected the resection margins macroscopically, obtained forceps biopsies of the resection margins, and attested that the removal was complete.
They also recorded whether the resection had been easy, moderately difficult, or difficult.
The use of narrow band imaging, chromoendoscopy, or argon plasma coagulation was not required by the study protocol but was allowed at the discretion of each gastroenterologist.
An expert gastrointestinal pathologist independently examined all the biopsies for residual adenomatous tissue, as well as to classify the polyps.
A total of 346 polyps (83%) were neoplastic.
Sixty-eight percent of these polyps were classified as tubular, tubulovillous, or villous adenomas. Twelve percent had a serrated histology, including 42 (10%) that were sessile serrated adenomas/polyps.
The expert reviewer found that overall, 10% of the neoplastic polyps were incompletely resected.
Large (10- to 20-mm) growths were more than twice as likely to be incompletely resected (17.3%) than were small (5- to 9-mm) growths (6.8%). Sessile serrated adenomas/polyps were four times more likely than other types to be incompletely resected (31% vs. 7%).
As a result, almost half (48%) of all large sessile serrated adenomas/polyps were incompletely resected.
"Because adenoma size is associated with both a higher prevalence of advanced histology and greater near-term risk of transition to cancer, incomplete resection of large neoplastic polyps is concerning," Dr. Pohl and his colleagues wrote.
No other factors were found to correspond with incomplete removal, including whether the resection was rated as difficult rather than easy, whether the polyps had to be removed piecemeal rather than all at once, whether the polyps were located in the right or left colon, and whether they had flat or other morphology.
"Our results raise questions regarding the quality of polyp resection and call for efforts to improve resection of neoplastic polyps, especially large polyps and sessile serrated adenomas/polyps," the researchers wrote.
In particular, increased attention to the polyp margin using special imaging may be warranted. Outlining and marking the margin before resection also might improve the completeness of the removal. And in some cases, adjunctive ablation of the margins after resection may be useful, they added.
The authors reported no relevant financial conflicts.