Background: Appendiceal neuroendocrine neoplasms (ANEN) are mostly indolent tumours treated effectively with simple appendectomy. However, controversy exists regarding the necessity of oncologic right hemicolectomy (RH) in patients with histologic features suggestive of more aggressive disease. We assess the effects of current guidelines in selecting the surgical strategy (appendectomy or RH) for the management of ANEN. Methods/Aims: This is a retrospective review of all ANEN cases treated over a 14-year period at 3 referral centres and their management according to consensus guidelines of the European and the North American Neuroendocrine Tumor Societies (ENETS and NANETS, respectively). The operation performed, the tumour stage and grade, the extent of residual disease, and the follow-up outcomes were evaluated. Results: Of 14,850 patients who had appendectomies, 215 (1.45%) had histologically confirmed ANEN. Four patients had synchronous non-ANEN malignancies. One hundred and ninety-three patients had index appendectomy. Seventeen patients (7.9%) had lymph node metastases within the mesoappendix. Forty-nine patients underwent RH after appendectomy. The percentages of 30-day morbidity and mortality after RH were 2 and 0%, respectively. Twelve patients (24.5%) receiving completion RH were found to have lymph node metastases. Two patients had liver metastases, both of them synchronous. The median follow-up was 38.5 months (range 1-143). No patient developed disease recurrence. Five- and 10-year overall survival for all patients with ANEN as the only malignancy was both 99.05%. Conclusions: The current guidelines appear effective in identifying ANEN patients at risk of harbouring nodal disease, but they question the oncological relevance of ANEN lymph node metastases. RH might present an overtreatment for a number of patients with ANEN.

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