Annual surveillance of serrated polyposis syndrome patients detected a relatively high rate of advanced adenomas and large serrated polyps, reported Dr. Yark Hazewinkel and colleagues in the July issue of Gastroenterology (doi.org/10.1053/j.gastro.2014.03.015).
"Due to a lack of prospective data, the optimal treatment approach with regard to surveillance intervals and polypectomy protocol [for this population] is still largely unknown," they wrote.
However, "considering the high polyp recurrence rate observed in our series, close endoscopic surveillance seems justified."
Dr. Hazewinkel of the Academic Medical Center in Amsterdam and colleagues looked at consecutive patients with serrated polyposis syndrome (SPS) who presented to their facility between January 2007 and December 2012.
Using the World Health Organization criteria for SPS, the investigators found that all patients had at least five histologically diagnosed serrated polyps proximal to the sigmoid colon, of which 2 measured 10 mm in diameter or more, and/or at least 20 serrated polyps spread throughout the colon.
In total, 50 patients were selected to undergo an index clearing colonoscopy with the goal of removing all polyps measuring 3 mm or more. This was achieved in 41 patients, who had a mean age of 57 years; 60% were male.
The remaining nine patients were referred for prophylactic surgery because of an "endoscopically untreatable number of polyps."
Ultimately, 37 patients underwent at least 1 surveillance colonoscopy, and a total of 119 colonoscopies were done over a median of 3.1 years of follow-up.
Looking at the primary outcome – detected cases of colorectal cancer – the authors tallied zero cases during surveillance colonoscopy in these patients.
Advanced adenomas were detected in 3 of the 37 patients (8%), with a median interval between last clearing colonoscopy and discovery of 13 months (range, 12-25 months), for a cumulative risk of 9% for detecting at least one advanced adenoma after three surveillance colonoscopies.
Meanwhile, large serrated polyps (defined as hyperplastic polyps or sessile serrated adenomas/polyps of 10 mm or greater) were detected in 11 of 37 patients (30%), with a median interval after clearing colonoscopy to detection of 21 months, for a cumulative risk of at least one large serrated polyp after three surveillance colonoscopies of 34%.
The authors said this study had several limitations, namely the small sample size and relatively short follow-up period.
Nevertheless, "the present study is the largest prospective study available, and the current findings add substantially to our understanding of the longitudinal [colorectal cancer] risk in SPS patients under strict endoscopic surveillance," they wrote.
In addition, of the 993 lesions removed between 3 and 5 mm in their cohort at clearing colonoscopy, none contained high-grade dysplasia or invasive cancer.
"Considering that patients with SPS have many diminutive lesions, leaving these lesions in situ until they reach a certain size (i.e., 6 mm) would substantially reduce the workload of the endoscopist and decrease the pathology costs, but the safety of this approach should first be prospectively assessed," the researchers wrote.
The authors disclosed no conflicts of interest relating to this study, which was supported by the Dutch Cancer Society.