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
04 Dec 2017
UK and Ireland Neuroendocrine Tumour Society