Introduction: Appendiceal NENs are usually diagnosed incidentally on histology following an appendicectomy. They include carcinoid tumours (appendiceal neuroendocrine tumours, NETs) and GCC. GCC neoplasms are able to transform to an adenocarcinoma phenotype. There are several important criteria to review when deciding on the treatment and follow up for appendiceal NENs, in particular when to offer further surgery to patients.
Aim: To assess whether the management of appendiceal NENs, including surgical management is appropriate, according to the histology of the appendicectomy specimen.
Method: A retrospective analysis of the prospectively kept NETs database was performed. Data including the type, staging, size and Ki-67 index of appendiceal NETs, and outcomes of right hemicolectomies (RHCs) was extracted.
Results: The database contained 74 patients: 51 well differentiated appendiceal NETs, 20 GCC, and unknown type in 3 patients. A completion RHC was performed in 23 patients with appendiceal NET: 10 patients had evidence of lymph node (LN) metastases, distant metastases or residual disease. 13 patients with GCC had a completion RHC performed.
Discussion: In the appendiceal NET group who had a completion RHC, cases where the size of the tumour had a T stage of pT1b (5 cases total), 2 patients had evidence of LN metastases but no residual disease seen in any of the patients. 2 of the 3 appendiceal NETs >2 cm where a RHC was performed, more advanced disease was seen with evidence of LN and distant metastases. Our data shows that GCCs are more aggressive, presenting at a later stage. 2 of 13 patients who had a completion RHC (GCC) had evidence of LN involvement in the RHC specimen and 1 patient had evidence of residual disease at the appendix base. 2 patients (GCC) who did not have a completion RHC, presented later with small bowel obstruction.
Conclusion: Our results show that GCC are more aggressive than appendiceal NETs, and therefore a more aggressive surgical approach should be considered. The definite management in cases (appendiceal NET group) that fall in the pT1b group, remains most challenging: in cases where the size was ≥1.5 cm and a RHC was performed, deeper local invasion was seen.
05 Dec 2016
UK and Ireland Neuroendocrine Tumour Society