Incomplete Polyp Resection Proves Tricky Business for Cancer Risk

Patients with incomplete colorectal polyp resections were at higher risk for more metachronous neoplasia and advanced neoplasia compared to patients who had a complete polyp resection, a post-hoc analysis suggested.

More neoplastic polyps were found in patients with incomplete resections compared to complete resections (mean 0.8 vs 0.3, P=0.008), and these incomplete segments were at higher risk of containing advanced neoplasia (18% vs 3%, P=0.034), reported Heiko Pohl, MD, MPH, from the VA Medical Center in White River Junction, Vermont, and colleagues.

Risk of metachronous neoplasia was higher in colorectal segments with incomplete resection compared to segments of complete resection (52% vs 23%, respectively, P=0.004), authors wrote in Annals of Internal Medicine.

The greatest independent risk factor linked to metachronous neoplasia was a history of at least one incomplete resection (OR 3.02, 95% CI 1.12-8.17). Increasing age was associated with a greater risk of metachronous neoplasia as well (OR 1.06 per year, 95% CI 1.01-1.10).

“We found that the risk for metachronous neoplasia after incomplete resection was approximately double the risk compared with segments with a previously complete resection,” Pohl and coauthors said.

With growing concerns of colorectal cancer arising from neoplastic polyps, incomplete surgical resection can be preventable. Up to 30% of colorectal cancers found after a colonoscopy can be attributed to incomplete polyp resection, the authors noted. Prior “clinically significant” polyps are of greatest concern.

“These findings are yet another reason for all colonoscopy to be of the highest quality,” David Greenwald, MD, of Mount Sinai Hospital in New York City, told MedPage Today.

“High-quality colonoscopy includes adequate colon preparation, adequate withdrawal time from the cecum to assure identification of all polyps, and complete removal of all identified adenomatous polyps,” said Greenwald, who was not involved with the study.

Researchers assessed the risk for colorectal neoplastic polyps (metachronous neoplasia) forming in colonic segments using colonoscopy after patients experienced a prior incomplete polyp resection. They examined data on 233 participants in the Complete Adenoma Resection (CARE) study who were treated at two medical centers from 2009 to 2012. The follow-up study also considered hyperplastic polyps as sessile serrated polyps if they were at least 10 mm and located proximal to the sigmoid colon.

Participants were included if they had a documented neoplastic colon polyp measuring 5 mm to 20 mm in size, a complete or incomplete resection, and a subsequent colonoscopy. The primary outcome included the proportion of colonic segments containing metachronous neoplasia initially observed by colonoscopy.

Participants were predominantly men (82.5%) with a mean age of 62. Median amount of time to colonoscopy was shorter in patients with incomplete resections (17 months [IQR 12-47] vs 45 months [IQR 35-62]).

There were 32 patients with an incompletely removed study polyp and 134 with completely removed study polyps. Of the 996 polyps available to analyze, 33 segments had any prior incomplete resection of a study polyp, while 181 had prior complete resection of a study polyp. Another 669 segments had no prior neoplastic polyp.

“We estimated that 28% … of segment metachronous neoplasia were attributable to incomplete resection,” the authors noted, with absolute rates between the incomplete and complete segments of 52% and 23%, respectively.

Study limitations included the lack of follow-up completion, which could promote potential bias in patient selection, lack of documented ethnicity, and the potential for more patients with routine colonoscopies to have less thorough examinations than those with a known history of an incomplete resection. One participant could also contribute multiple colonic segments, requiring multiple comparative analyses.