Endocrine Abstracts

Introduction: Appendiceal neuroendocrine neoplasms (ANEN) account for approximately 50% of all primary tumors of the appendix and are between the first and third-most frequent gastrointestinal neuroendocrine neoplasms. Data regarding trends in incidence, management and prognosis of ANEN is limited.

Aims: To evaluate temporal trends in ANEN incidence, evaluation and management over a 13-year period.

Materials and methods: Appendectomy pathology reports from a single tertiary center were reviewed. Epidemiological, clinical and pathological data of ANEN patients were collected from electronic patient files.

Results: Between January 2005 and December 2018, 8,327 appendectomies were performed. A total of 57 ANENs were diagnosed. Theirmean age was 31.7 ± 49 years; 70.2% were females; 17.5% were of Arab ethnicity; and 22.8% werediagnosed under 18 years of age.

The cohort was subdivided according to year of diagnosis into Period A (2005–2011) and Period B (2012–2018). No differences were found in ANEN incidence ( Period A 0.68% and Period B 0.62%, respectively, P = 0.104) or epidemiologic characteristics between periods. Pathologic features were similar in the two subgroups, although pathology reports were more comprehensive and applicable to international guidelines in Period B. More patients in Period B were followed in dedicated clinics. Somatostatin receptor imaging and biochemical studies such as serum Chromogranin A and urinary 5-Hidroxy-indol-acetic acid (5-HIAA) was also more frequently used in Period B. Fifteen patients underwent right hemicolectomy (8/31 in period A, 7/26 in period B, P = 0.925). Pathologic features of ANEN were similar between the two subgroups. Residual disease in hemicolectomy specimen was observed in 2/7 patients in Period A and 3/6 patients in Period B. For the duration of follow up (10.8 ± 1.7 years in Period A and 3.5 ± 1.9 years in Period B, P < 0.001) all patients remained alive, and all patients except one remained disease free.

Conclusions: Over a 13-year period, no distinct temporal changes in epidemiological, clinical or pathological features of ANENs were noted. Although after 2011 the clinico-pathological evaluation was more detailed and elaborated, there was no change in hemicolectomy rate or disease prognosis. Large scale studies are needed, in order to consider revision of current international guidelines for ANEN evaluation and treatment, in particular the necessity of right hemicolectomy.