The slow progressive nature of duodenal neuroendocrine tumor: a case report of long-term observation over 14 years

Duodenal neuroendocrine neoplasms with unexpectedly aggressive behaviour: Challenging the "watch and wait" approach

The incidence of duodenal neuroendocrine neoplasms has risen over the past decades as a result of the wide availability of endoscopy and associated expertise. Although it is considered that tumour size greater than 10 mm, higher tumour grade and/or location in relation to the ampulla of Vater represent the main risk factors for local or distant metastases, we describe two cases of well differentiated grade 1 and grade 2 neuroendocrine tumours, which measured < 10 mm at the time of diagnosis but had an aggressive course during follow-up. Furthermore, we also summarise the available therapeutic strategies for the management of small, low grade, non-functioning, non-ampullary duodenal neuroendocrine neoplasms.

A "Watch and Wait" Strategy Involving Regular Endoscopic Surveillance Is Safe for Many Patients with Small, Sporadic, Grade 1, Non-Ampullary, Non-Functioning Duodenal Neuroendocrine Tumours

INTRODUCTION

Duodenal neuroendocrine tumours (d-NETs) are rare but are increasing in incidence. Current ENETS guidelines advocate resection of all localized d-NETs. However, "watch and wait" may be appropriate for some localized, small, grade 1, non-functioning, non-ampullary d-NETs. We evaluated whether patients with such d-NETs who chose "watch and wait" involving regular endoscopic surveillance had equivalent disease-related outcomes to patients undergoing endoscopic or surgical resection.

METHODS

Retrospective review of patients with histologically confirmed d-NETs at Liverpool ENETS Centre of Excellence 2007-2020.

RESULTS

Sixty-nine patients were diagnosed with d-NET of which 50 were sporadic, non-functioning, non-ampullary tumours. Patient treatment groups were similar in terms of age, gender, and tumour location and grade, but unsurprisingly, larger tumours (median diameter 17 mm [p < 0.0001]) were found in the surgically treated group. Five patients underwent surgical resection with no evidence of tumour recurrence or disease-related death. Twelve patients underwent endoscopic resection (ER), with 1 local recurrence detected during follow-up. Thirty patients (28 with d-NETs ≤10 mm) underwent "watch and wait" with resection only if tumours increased in size. The d-NETs in 28/30 patients remained stable or decreased in size over a median 27 months (IQR: 15-48, R: 3-98). In 7 patients, the d-NET was completely removed by avulsion during diagnostic biopsy and was not seen at subsequent endoscopies. Only 2 patients showed increased d-NET size during surveillance, of whom only one was fit for ER. No NET-related deaths were documented during follow-up.

CONCLUSIONS

All of the localized, ≤10 mm, grade 1, non-functioning, non-ampullary d-NETs in this cohort behaved indolently with very low risks of progression and no tumour-related deaths. "Watch and wait," therefore, appears to be a safe alternative management strategy for selected d-NETs.