Appendiceal neuroendocrine tumours, when to operate?

Abstract

Appendix neuroendocrine tumours (ANETs) carry variable risk depending on histopathological risk factors. Completion right hemicolectomy (RH) is recommended for tumours over 2 cm, with those under 1 cm considered cured by appendectomy. Evidence for RH in ANETs between 1 and 2 cm is unclear. To determine if a non-surgical approach is appropriate for patients with well-differentiated 1-2 cm ANETs, alongside reviewing outcomes for under 1 cm and over 2 cm tumours. A retrospective cohort study of all ANETs resected by index appendicectomy in Auckland between 1995 and 2012, using the New Zealand NETwork! registry. Two hundred and four patients with ANETs met inclusion criteria; 157 under 1 cm (77%), 40 between 1 and 2 cm (20%), 7 over 2 cm (3.4%). RH was performed in 20 patients, seven in the under 1 cm cohort, 9 in the 1-2 cm cohort and 4 in the over 2 cm cohort. One patient with an over 2 cm ANET had subsequent RH histology demonstrating lymph node metastasis. Follow-up was radiological, median follow-up 62 months (range 2-204). Eight 1-2 cm ANETs had histological risk factors but did not undergo RH and had no evidence of recurrence or metastasis on follow-up. No patients died from their ANET. Patients' with ANETs under 2 cm did not exhibit metastases. Our data support RH in patients' with ANETs over 2 cm and a more conservative approach in those under 2 cm.