Background: Neuroendocrine tumours of the appendix (ANET) are relatively indolent tumours typically identified incidentally at surgery for suspected appendicitis. The role of right hemicolectomy (RH) for tumours with high risk features is debated. We compared the management of ANET at three centres against ENETS criteria for therapy selection.
Methods: Retrospective review of all patients diagnosed with ANET at three tertiary centres. Patients that underwent appendicectomy alone or as part of another abdominal operation were reviewed patients with histologically confirmed ANET were identified. All other histology types were excluded. Patient demographic, operative, biochemical/radiological, and follow-up data were extracted from a prospectively maintained database.
Results: Of 14,850 patients undergoing appendicectomy, 215 (1.45%) were diagnosed with ANET. There were 85 males (39.5%) and 130 females (60.5%). Regarding tumour size, 95 (44.2%) were <1 cm, 69 (32.1%) were 12 cm, and 51 (23.7%) were >2 cm. Two hundred (92%) patients had grade 1 tumours, whereas 9 (4.2%) and 1 (0.5%) had grade 2 and 3 tumours, respectively (data for five patients unavailable). Regarding index operation, 193 (89.8%) underwent appendicectomy, others: index RH (n=16, 7.4%), sub-total colectomy (n=1, 0.5%), panproctocolectomy (n=2, 0.9%), or appendicectomy at laparoscopy for gynaecological indication (n=3, 1.4%). Seventeen patients that underwent appendicectomy (7.9%) had involved lymph nodes. Sixty-four patients met ENETS criteria for completion RH (after appendicectomy) due to high risk features. Forty-nine patients underwent completion RH, twelve of which (24.5%) had metastasis to the lymph nodes. No patients developed imaging detectable lymph node metastases, recurrence or died, regardless of whether they underwent completion hemicolectomy (n=49) or not (n=15). Two patients (<1%) had distant metastases. Four patients had additional, primary tumours. In patients with ANET as the sole primary tumour, within a median follow-up of 38.5 months (range 1143), no patient exhibited any evidence of recurrence: 5- and 10-year overall survivals were 99.05%.
Conclusions: ENETS guidelines appear to identify patients at higher risk of nodal metastasis, however the oncological relevance of lymph node metastases in ANET is questionable. In most patients with ANET, right hemicolectomy may represent over-treatment.
04 Dec 2017
UK and Ireland Neuroendocrine Tumour Society