ISSN 1470-3947 (print) | ISSN 1479-6848 (online)

Endocrine Abstracts (2017) 52 P20 | DOI: 10.1530/endoabs.52.P20

Prophylactic right hemicolectomy in Appendiceal Neuroendocrine Neoplasms: challenging the current indications

Michail Galanopoulos1, Rory McFadyen2, Nick Evans2, Rishi Naik2, Ioanna Drami3, Massimo Varcada3, Olagunju Ogunbiyi3, Tu Vinh Luong4, Jennifer Watkins4, Ian Clark4, Faidon Laskaratos1, Dalvinder Mandair1, Martyn Caplin1 & Christos Toumpanakis1

1Neuroendocrine Tumour Unit, ENETS Centre of Excellence, Royal Free Hospital, London, UK; 2Medical School, University College of London, London, UK; 3Department of Colorectal Surgery, Royal Free Hospital, London, UK; 4Histopathology Department, Royal Free Hospital, London, UK.

Introduction: To prevent loco-regional recurrence and subsequent development of distant metastases in Appendiceal Neuro-Endocrine Neoplasms (ANEN), the existing Guidelines have suggested several criteria for a prophylactic right hemicolectomy, following the initial appendectomy. However, some of those criteria seem rather arbitrary and have not been validated by large studies.

Aim: To assess the outcomes of prophylactic right hemicolectomy (RHC), focusing on regional lymph nodal invasion.

Materials and methods: Over a 10-year period, 263 patients with ANEN were identified. Patients with ‘goblet cell tumours’ or ‘mixed adenoneuroendocrine carcinomas’ were excluded. Patients who underwent RHC were categorized into Group A (GA): those with lymph nodal invasion (LNI) at RHC and Group B (GB): those without LNI. The original tumour size, tumour location, margin invasion, proliferation rate, meso-appendiceal invasion (MAI), as well as angioinvasion and lymph vessels invasion were assessed.

Results: Based on Guidelines’ recommendations, 72/263 (27%) patients underwent prophylactic RHC. GA included 23 patients (32%), and GB had 49(68%). All patients from both groups had R0 appendectomy. 30.5% tumours from GA and 45% from GB were measuring less than 1 cm, 30.5% from GA and 31% from GB were measuring between 1 and 2 cm, whilst 39% from GA and 24% of GB, had tumours measuring more than 2 cm. Location at appendiceal base was demonstrated in 22% from GA, but only in 8% from GB. Deep (more than 3 mm) MAI was noted in 13% of GA and in 6% of GB. Angioinvasion and lymph vessel involvement were demonstrated in 30 and 57% from GA, in comparison with 10% and 8% from GB, respectively. Finally, 35% patients from GA and only 2% of GB had grade 2 tumours.

Conclusions: A significant percentage of patients had lymph nodal invasion at the time of prophylactic RHC for ANEN. Grade 2 tumours, angioinvasion and lymphatic invasion, location at appendiceal base and size more than 2 cm seem to be the most important risk factors. Larger studies with prolonged follow-up are needed, to identify the actual role of lymph nodal invasion to the overall disease prognosis.

Keywords: appendix; Neuroendocrine neoplasm; lymph nodes metastases; appendectomy; right hemicolectomy