SAN ANTONIO – Patients with both sessile serrated polyps and adenomatous polyps appeared to have a higher risk for more aggressive colorectal cancer than do those with a lesion from one pathway or the other, based on data from 433 adults gleaned from more than 17,000 baseline colonoscopies. The findings were presented at the annual meeting of the American College of Gastroenterology.
Adenomas and advanced serrated polyps (ASPs) are both precursors to colorectal cancer via different molecular pathways, said Dr. Carol Burke of the Cleveland Clinic. But the association between adenomas and ASPs (including serrated adenomas and sessile serrated polyps) is not well understood.
To determine the phenotypes in patients with different types of polyps, Dr. Burke and colleagues compared baseline polyp characteristics of individuals who were undergoing their first lifetime colonoscopies.
The researchers reviewed 17,550 colon polyp pathology reports from patients seen between April 2004 and November 2007. The final study cohort included 180 individuals with sessile serrated polyps (SSPs) only, 80 individuals with SSPs plus adenomas, and 173 with adenomas only. Individuals with incomplete exams, and those with a history of colectomy, colorectal cancer, or hereditary colorectal cancer syndrome were excluded.
The coexistent SSP/adenoma group was significantly more likely to have three or more adenomas than was the adenoma-only group (21% vs. 10%) and significantly more likely to have sessile serrated polyps measuring 10 mm or larger than was the SSP-only group (66% vs. 44%).
More adenomas in each group were located in the proximal colon than in the distal colon, although the percentages of polyps in each location were not significantly different between the SSP/adenoma group and the adenoma-only group. The size of adenomas was not significantly different between the two groups.
Pathological data showed significant differences between the SSP/adenoma group and adenoma-only group. The incidence of both tubular adenoma with high-grade dysplasia and tubulovillous adenoma with high-grade dysplasia was 3.8% in the SSP/adenoma group, compared with 0.6% and 2.3%, respectively, in the adenoma-only group. There were no significant differences in serrated polyp pathology between the SSP/adenoma group and the SSP-only group.
The results suggest that advanced serrated polyps should be considered equal in risk to adenomas in the planning of postpolypectomy surveillance, Dr. Burke said.
The average age in the SSP-only, SSP-plus-adenomas, and adenomas-only groups was 57 years, 61 years, and 58 years, respectively. The average body mass index was approximately 29 kg/m2 in all three groups, which is considered to be overweight. The proportion of women in the three groups was 42%, 44%, and 49%, respectively.
The mean age of individuals with only SSPs was significantly younger than in the other two groups, Dr. Burke noted, but the implications of this difference were not clear.
Dr. Burke said that she had no financial disclosures related to her presentation at the meeting.