Endocrine Abstracts (2019) 68 P10 | DOI: 10.1530/endoabs.68.P10

Type III gastric neuroendocrine neoplasms: moving towards less-extensive resections in selected cases?

Klaire Exarchou1, Lukasz Kameniarz2, Alexandra Victor3, Mohid Khan4, Raj Srirajaskanthan3, Dalvinder Mandair2, John Ramage3, Martyn Caplin2, David Mark Pritchard1 & Christos Toumpanakis2

1Institute of Translational Medicine, University of Liverpool and Liverpool ENETS Centre of Excellence, Liverpool University Hospitals NHS Foundation Trust, Liverpool, UK; 2Neuroendocrine Tumour Unit – Centre for Gastroenterology, ENETS Centre of Excellence, Royal Free Hospital, London, UK; 3Department of Gastroenterology, Institute of Liver Studies & NET Centre, ENETS Centre of Excellence, Kings College Hospital, London, UK; 4South Wales NET Service, University Hospital of Wales, Cardiff, UK

Background: Type III gastric neuroendocrine neoplasms (g-NEN) are usually lesions of higher grade and often associated with loco-regional and distant metastases. Guidelines recommend partial or total gastrectomy with local lymph node resection. Data for less-extensive resections are limited.

Aim: To assess whether advanced endoscopic excision [Endoscopic Mucosal Resection (EMR) or Endoscopic Submucosal Dissection (ESD)] or localized surgical approach (wedge resection) is sufficient and not associated with disease recurrence at follow-up.

Methods: Thirty five patients with type III g-NEN of grade 1 and 2 were included. All patients had appropriate staging at diagnosis and had been under regular endoscopic and radiological follow-up.

Results: The average age of patients at diagnosis was 56 years. Average follow-up was 41.5 months. Mean tumour size was 1.77 cm and most common location was gastric body (80%). Most tumours (91%) had Ki67 < 10%. In 8/35 (23%) a total/subtotal/partial gastrectomy was performed with no tumour recurrence. In 6/35 (17%) with mean tumour size 1.3 cm and Ki67<10%, EMR or ESD was performed. No recurrence was noted at follow-up (average: 35.6 months). Wedge resection was performed in 15/35 (43%) patients. In 14 patients, no recurrence has been noted (average follow-up 42.1 months). Hepatic metastases were detected and resected in 1 patient, with tumour size >2 cm, 96 months post-wedge resection. This patient has been tumour-free, 36 months post-hepatectomy. Active surveillance was offered in 4/35 (11%) with grade 1 tumours, measuring < 1 cm, with no signs of disease progression at follow-up. The same outcome was noted in 2 patients, who, due to co-morbidities, did not have an intervention and were treated with long-acting somatostatin analogues. Tumour size (P: 0.0018), but not tumour grade, seemed to be associated with lymph nodal metastases, detected post-resection in 38% patients.

Conclusions: A proportion of type III g-NEN seems be associated with less-aggressive biologic behavior. In type III g-NEN, measuring less than 2 cm with Ki67 < 10%, either EMR/ESD or wedge resection, seems sufficient. Larger series are needed to identify more accurately: a) patients who are suitable just for endoscopic excision and b) further risks factors for lymph-nodal or distal metastases.