European Neuroendocrine Tumor Society (ENETS) 2023 guidance paper for colorectal neuroendocrine tumours.

This ENETS guidance paper, developed by a multidisciplinary working group, provides an update on the previous colorectal guidance paper in a different format. Guided by key clinical questions practical advice on the diagnosis and management of neuroendocrine tumours (NET) of the caecum, colon, and rectum is provided. Although covered in one guidance paper colorectal NET comprises a heterogeneous group of neoplasms. The most common rectal NET are often small G1 tumours that can be treated by adequate endoscopic resection techniques. Evidence from prospective clinical trials on the treatment of metastatic colorectal NET is limited and discussion of patients in experienced multidisciplinary tumour boards strongly recommended. Neuroendocrine carcinomas (NEC) and mixed neuroendocrine non-neuroendocrine neoplasms (MiNEN) are discussed in a separate guidance paper.

Gastroenteropancreatic Neuroendocrine Neoplasms in Patients with Inflammatory Bowel Disease: An ECCO CONFER Multicentre Case Series.

BACKGROUND: Gastroenteropancreatic neuroendocrine neoplasms [GEP-NENs] have rarely been reported in association with inflammatory bowel diseases [IBDs]. METHODS: An ECCO COllaborative Network For Exceptionally Rare case reports project [ECCO-CONFER] collects cases of GEP-NENs diagnosed in patients with IBD. RESULTS: GEP-NEN was diagnosed in 100 IBD patients; 61% female, 55% Crohn's disease, median age 48 years (interquartile range [IQR] 38-59]). The most common location was the appendix [39%] followed by the colon [22%]. Comprehensive IBD-related data were available for 50 individuals with a median follow-up of 30 months [IQR 11-70] following NEN diagnosis. Median duration of IBD at NEN diagnosis was 84 months [IQR 10-151], and in 18% of cases NEN and IBD were diagnosed concomitantly. At diagnosis, 20/50 were stage-I [T1N0M0], and 28/50 were graded G1 [ki67 ≤2%]. Incidental diagnosis of NEN and concomitantly IBD diagnosis were associated with an earlier NEN stage [p = 0.01 and p = 0.02, respectively]. Exposure to immunomodulatory or biologic therapy was not associated with advanced NEN stage or grade. Primary GEP-NEN were more frequently found in the segment affected by IBD [62% vs 38%]. At the last follow-up data, 47/50 patients were alive, and only two deaths were related to NEN. CONCLUSIONS: In the largest case series to date, prognosis of patients with GEP-NEN and IBD seems favourable. Incidental NEN diagnosis correlates with an earlier NEN stage, and IBD-related therapies are probably independent of NEN stage and grade. The association of GEP-NEN location and the segment affected by IBD may suggest a possible role of inflammation in NEN tumorigenesis.