Endocrine Abstracts

Introduction: Small bowel NETs (SBNETs) are a group of heterogenous tumours that can exist as unifocal or multifocal disease. The current literature regarding multifocal SBNETs includes small patient cohorts and mainly focuses on histopathologic characteristics only. Data regarding the presenting symptoms and survival are lacking.

Aim: To present clinical characteristic, disease free survival (DFS) and overall survival (OS) in patients with multifocal SBNETs.

Method: A retrospective search in a prospective maintained database of all patients with SBNETs, between December 2010 and December 2023, was performed. Datasets of patients with multifocal tumours were included, and additional clinical data and survival data were collected.

Results: We identified n = 88 patients, out of whom 49 were male (56%) with median age of 67.5 (IQR 58 – 74). A total of 40 patients (45%) were found to have liver metastases and n = 9 patients (10%) had bone metastases at the moment of SBNET resection. The median number of tumours in pathology reports was 3 (IQR: 2 - 6) and the median maximum size of a tumour was 2cm in diameter (IQR: 1.5 – 3cm). In pathology reports, n = 72 (82%) patients had G1 tumour, n = 15 (17%) patients had G2 tumours and n = 1 patient (1%) had a G3 tumour. Mesenteric fibrosis was documented in n = 43 patients (49%). The presenting symptoms were: incidental finding in n = 45 patients (51%), abdominal pain in n = 21 patients (24%), symptoms of a NET in n = 16 patients (18%), and obstruction in n = 6 patients (7%). There was progressive disease found in n = 35 patients (40%), and the median disease free survival was 36.5 months (IQR: 17 – 79 months). The overall survival was 61 months (IQR: 26 - 90 months) with only n = 5 patients dying within the first 12 months after the surgery.

Conclusion: This study contains the largest cohort describing the presenting symptoms, characteristics and survival data of patients with multifocal SBNETs. Future research should focus on the differences between patients with unifocal SBNETs to offer patients with multifocal SBNETs the most appropriate treatment and follow up.