Endocrine Abstracts

JOINT540

Introduction: The global incidence of neuroendocrine neoplasms (NENs) is increasing worldwide, however most studies are based on cancer-registry data, with different data collection methods, making it difficult for cross-country comparisons. Our study aims to analyze the incidence and survival of NENs in a well-defined population of the Maltese islands based on histological and radiological data.

Methods: A retrospective analysis of patients diagnosed histologically or radiologically with NEN at Mater Dei Hospital, the only central national service hospital in Malta, between 1^st January 2015 and 31^st December 2020, was performed. Detailed clinical, histopathological and radiological data was obtained. Patients were followed up till 31^st December 2024 or death, whichever came first. Age- and sex-adjusted standardized incidence rates (SIRs), prevalence and mortality rates were calculated.

Results: A total of 435 patients were identified, of which 237 (54.48%) were males. The median age at diagnosis was 68 years (IQR 59-74). The overall age-adjusted SIR was 8.78/100,000/year, with a male-to-female ratio of 1.2:1. The age-adjusted SIR of bronchopulmonary NEN (BP-NEN) was 2.77/100,000/year whilst that of gastro-enteropancreatic NEN (GEP-NEN) was 4.02/100,000/year. The 6-year limited duration prevalence rate was 43.7/100,000. The most frequent location of GEP-NEN was the pancreas (11.26%) followed by the appendix (7.13%) and rectum (5.98%) whilst the duodenum (2.76%) and the oesophagus were the less frequent (0.69%). Well-differentiated Grade 1 GEP-NEN prevailed at 63.74%, followed by Grade 2 at 8.24% and Grade 3 at 7.69%. Poorly differentiated neuroendocrine carcinoma was found in 7.14% of the patients. Most tumours were localized (57.59%) with 28.02% having disseminated disease at presentation. Distant metastasis were most commonly observed in NEN of the jejunum and ileum (27.45%) and the rectum (21.57%). Two hundred and forty-five patients (56.32%) passed away during the study period. The standard mortality ratio (SMR) of all NEN was 4.59 (95% CI 4.02-5.17). A higher mortality was observed in BP-NEN, which had an SMR of 6.52 (95% CI 5.35-7.68), compared to GEP-NEN, which had an SMR of 3.68 (95% CI 2.3-4.56). Univariate analysis revealed a statistically significant association between mortality and male gender (p 0.001), age at diagnosis (P<0.001), primary site (P<0.001), grade (P<0.001), stage (P<0.001) and Ki67 (P<0.001).

Conclusion: This is the first study reporting the incidence, prevalence and survival rates of NEN in the Maltese Islands. Our findings suggest that GEP-NEN and BP-NEN incidence and survival in the Maltese Islands is comparable to that observed in other countries.