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Is Right Hemicolectomy Justified in Patients With Neuroendocrine Neoplasms of the Appendix?
Nikhil Pawa2, Helai Osmani2, Panagiotis Drymousis1, Dimitrios Patsouras2, Ashley K. Clift1, Alan Baird2, Omar Faiz2, Anthony Antoniou2, Andrea Frilling*1
1Imperial College London, London, United Kingdom; 2St Mark's Hospital, London, United Kingdom
Introduction: Appendiceal neuroendocrine neoplasms (ANEN) are steadily increasing in incidence. Although typically indolent, their ability to metastasize is recognized. The mainstay of ANEN treatment is surgery, but controversy exists regarding appropriate surgical strategy for disease control, i.e. appendectomy as the only treatment or right hemicolectomy (RH). Recommendations regarding indications for completion RH are inconsistent, especially for intermediate sized lesions.
Methods: Retrospective review of all appendectomies undertaken at 2 centers between Jan 2003-Sept 2014. Patients with histologically confirmed ANEN underwent baseline work up for NEN and were staged according to the European Neuroendocrine Tumor Society (ENETS) classification. Tumor grading was as per the ENETS grading system. Decision for completion RH was based on histological findings in appendectomy specimens. We compared indications of those undergoing RH with the 2012 ENETS guidelines. Last follow-up for all ANEN was in Jan 2015.
Results: Within the study period, 7118 appendectomies were performed. Of these, 126 (1.8%) patients had ANEN, 12 were diagnosed during abdominal surgery for other indications. Mean age of this group was 32.8 years (range 11-79). Mean tumor size was 9.8mm (range 1-50) - 48% of patients had T1 tumors (<10mm), 17% had T2 tumors (10-20mm), and 35% had T3 or larger tumors (>20mm). Twenty-four patients (19%) subsequently underwent RH based on ENETS recommendations. Three of those undergoing RH had T1 lesions, 11 had T2 and 10 had T3 or above lesions. Eight (33%) had lymph node metastases, of which 5 originated from T1/2 primary tumours. Of the total cohort, no patients had any distant metastases at initial presentation or follow-up. After a median follow-up of 9months post-RH (range 1-89), no patients developed disease recurrence. Two patients died (at 13 and 31 months, respectively) after an initial RH for known small bowel carcinoid wherein ANEN were incidentally identified. There were no deaths related to ANEN. According to the current ENETS guidelines, 6 additional patients should have underwent further resection.
Discussion: The ENETS consensus guidelines for ANEN appear appropriate for selecting patients for completion RH as lymph node metastases can be expected in one third of them. However, the biological significance of lymph node metastases in ANEN is questionable, given that there were no instances of disease recurrence in these patients and also not in those patients who would fulfil the criteria for completion hemicolectomy but stayed with appendectomy only. A randomised control trial comparing RH with appendectomy only in patients fulfilling the ENETS criteria for more extensive surgery would be needed; however its feasibility would be questionable due to very long follow-up required.
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