Purpose: Rectal neuroendocrine tumours (NETs) often present as an incidental finding during colonoscopy. Complete endoscopic resection of low-grade NETs up to 10 mm is considered safe. Whether this is also safe for NETs up to 20 mm is unclear. We performed a nationwide study to determine the risk of lymph node and distant metastases in endoscopically removed NETs. Methods: All endoscopically removed rectal NETs between 1990 and 2010 were identified using the national pathology database (PALGA). Each NET was stratified according to size, grade and resection margin. Follow-up was until February 2016. Results: Between 1990 and 2010, a total of 310 NETs smaller than 20 mm were endoscopically removed. Mean size of NETs was 7.4 mm (SD 3.5). In 49% of NETs (n = 153), no grade (G) could be assessed from the pathology report, 1% was G2 (n = 3), and the remaining NETs were G1. Median follow up was 11.6 years (range 4.9–26.0). During follow-up, 30 patients underwent surgical resection. Lymph node or distant metastasis was seen in 3 patients (1%) which all had a grade 2 NET. Mean time from endoscopic resection to diagnosis of metastases was 6.1 years (95% CI 2.9–9.2). Conclusion: No lymph node or distant metastases were seen in endoscopically removed G1 NETs up to 20 mm during the long follow-up of this nationwide study. This adds evidence to the ENET guideline that endoscopic resection of G1 NETs up to 20 mm appears to be safe.

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doi.org/10.1007/s00384-020-03801-w, hdl.handle.net/1765/131744
International Journal of Colorectal Disease: clinical and molecular gastroenterology and surgery
Department of Pathology

Kuiper, T. (Teaco), van Oijen, M.G.H, van Velthuysen, M.F. (M. F.), Van Lelyveld, N, van Leerdam, M.E, Vleggaar, F.D. (F. D.), & Klümpen, H.J. (2020). Endoscopically removed rectal NETs: a nationwide cohort study. International Journal of Colorectal Disease: clinical and molecular gastroenterology and surgery. doi:10.1007/s00384-020-03801-w