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.