Large interobserver variation between pathologists in differentiating sessile serrated polyps (SSPs) from hyperplastic polyps (HPs) is well described. The limited reliability of pathologic interpretation, combined with limited data on surveillance of patients with serrated lesions, as well as variable interpretation of the importance of specific literature findings and differing tolerance of risk, have led to variations in guideline recommendations for surveillance colonoscopy after serrated lesion resection.
For example, the U.S. Multi-Society Task Force on Colorectal Cancer guideline incorporates the pathologic interpretation of serrated class lesions as HPs or SSPs. SSPs ≥10 mm or having dysplasia are considered high-risk lesions for which colonoscopy is repeated in 3 years. Patients with 1 or 2 SSPs without dysplasia and <10 mm in size are considered similar to the low-risk adenoma group. In the European guideline, no reliance is placed on the pathologic differentiation of SSPs from HPs. Any serrated lesion 10 mm or larger or with dysplasia is considered high risk, for which colonoscopy in 3 years is recommended. Smaller SSPs and HPs are considered low risk, for which colonoscopy should be repeated in 10 years.
In a post-hoc simulation study of patients undergoing colonoscopy in Norway, the two guidelines were applied to see how much variation in surveillance intervals they produced. The answer was very little. Of all screened participants, 98% received the same recommendation from both guidelines (Κ=0.9). For patients with ≥1 serrated polyp, the agreement in surveillance interval was still 90% (K=0.8). Much of the concordance in surveillance intervals appeared to be driven by the guideline implications of synchronous adenomas.
We’ve seen several recent interesting studies showing that the number and size of polyps alone, without reference to any histology, will lead to application of surveillance intervals that have substantial concordance to those that consider histology. This particular study suggests that the large interobserver variation between HPs and SSPs among pathologists has less implication for surveillance intervals than would be expected.
Bleijenberg A, Klotz D, Loberg M, et al. Implications of different guidelines for surveillance after serrated polyp resection in United States of America and Europe. Endoscopy
2019 June 13. (Epub ahead of print) (https://doi.org/10.1055/a-0916-8598