The impact of lymph node metastases and right hemicolectomy on outcomes in appendiceal neuroendocrine tumours (aNETs)

Introduction: European Neuroendocrine Tumour Society (ENETS) recommends managing appendiceal neuroendocrine tumours (aNET) with appendicectomy and possibly completion right hemicolectomy (CRH). However, disease behaviour and survival patterns remain uncertain. Materials and methods: We retrospectively assessed the impact of lymph nodes and CRH on outcomes, including survival, in all aNET patients diagnosed between 1990 and 2016. Results: 102 patients (52F, 50 M), median age 39.4 (range 16.3-81.1) years, were diagnosed with aNET. Mean tumour size was 12.7 (range 1-60) mm, most sited in appendiceal tip (63%). Index surgery was appendicectomy in 79% of cases while the remainder underwent colectomy. CRH performed in 30 patients at a median 3.2 (range 1.4-9.8) months post-index surgery yielded residual disease in nine: lymph nodes (n = 8) or residual tumour (n = 1). Univariate logistic regression showed residual disease was significantly predicted by tumour size >2 cm (p = 0.020). Four patients declined CRH, but did not suffer relapse or reduced survival. One patient developed recurrence after 16.5 years of follow-up and another patient developed a second neuroendocrine tumour after 18.8 years follow-up. There were 5 deaths; one being aNET-related. 5-year and 10-year overall survival were 99% and 92% respectively; 5-year and 10 year relapse-free survival were 98% and 92% respectively. Only 5-year relapse-free survival was affected by ENETS stage (p = 0.002). Conclusion: aNETs are indolent with very high rates of overall and relapse-free survival. Recurrence is rare, and in this series only occurred decades later, making a compelling case for selective surveillance and follow-up. The significance of positive lymph nodes and the necessity for completion right hemicolectomy remain unclear. (c) 2020 Elsevier Ltd, BASO The Association for Cancer Surgery, and the European Society of Surgical Oncology. All rights reserved.