AB153. SOH23ABS_228. A retrospective review of patients with primary appendiceal neoplasms and the best practice guidance for the management of these tumors

Background: Appendiceal neoplasms include a heterogeneous group of tumors that exhibit varying malignant potential. Neuroendocrine tumors (NET) of the appendix are the most common type. The surgical outcomes of appendiceal neoplasms depend on the location, grade, size of tumor, positive lymph nodes and metastasis. For metastatic disease and peritoneal invasion, cytoreductive surgery (CRS) and hyperthermic Intraperitoneal Chemotherapy (HIPEC) have become the standard of care, but the need for this therapy can be a challenging decision. Multidisciplinary teams (MDTs) often have a large role to play in the discussion and management of individual patient care.

Methods: A retrospective review of a prospectively maintained gastrointestinal oncology database of 1,408 patients in our institution was conducted ranging from 2018 to 2022. Patients with histologically confirmed neoplasms of the appendix were identified. Patients with a non-appendix primary were excluded from the analysis. A total of 32 people were found to have primary appendiceal neoplasms, and this data was used in the study.

Results: A total of 32 patients were diagnosed with a primary appendix neoplasm over the study period (n=32). The incidence rate was 0.17, with a total of 767 appendicectomies performed over this period. Of the total cohort, five were aged <18 years at time of index surgery. Pseudomyxoma peritonei was the presenting complaint in two patients. Low grade appendiceal mucinous neoplasms (LAMN) and well differentiated neuroendocrine tumours (NETs) were the most commonly represented pathology (11 per group), with 6 mucinous adenocarcinomas, 3 goblet cell adenocarcinomas and 1 benign schwannoma. A proportion of 71% (23) were treated with appendicectomy or caecectomy as their index surgical procedure. Of these 8 proceeded to further surgery (7 completion right hemicolectomy, 1 cytoreduction and HIPEC). Five patients were referred to the national NET MDT, of which three were paediatric patients.

Conclusions: The majority of patients with benign appendix neoplasms may be effectively managed via the local MDT. Consideration of referral to the national NET MDT or CRS-HIPEC unit should be considered for paediatric patients or those presenting with advanced disease.

Keywords: Appendix neoplasms; multidisciplinary management; neuroendocrine tumours; carcinoid tumours; hyperthermic intraperitoneal chemotherapy (HIPEC)