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.

Endoscopic resection, Neuroendocrine tumour, Rectum, Recurrence
dx.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