Endocrine Abstracts

JOINT985

Background: Neuroendocrine tumors (NETs) mostly affect the gastro-entero-pancreatic system and then the lungs. One significant clinical phenomenon observed in patients with NETs is the increased prevalence of synchronous or metachronous secondary primary neoplasms (SPMs), mainly gastrointestinal, raising questions about whether these occurrences are coincidental or reflect underlying genetic factors.

Materials and Methods: A retrospective observational study was conducted on a cohort of 93 patients diagnosed with neuroendocrine neoplasms in our department between January 2018 and January 2025. Data including demographics, histopathological and immunohistochemical profiles, imaging findings, and treatment details were collected from medical records.

Results: Twelve patients were diagnosed with SPMs and there were 14 distinct types of neoplasms identified. Among these, 50% of SPMs were diagnosed prior to the detection of NETs. There were 7 males (58.3%), 5 females (41.7%) and the mean age was 58.8 years. The most frequent SPM sites included the biliary (3 cases) and genitourinary (3 cases) tracts. There were three patients with multiple endocrine neoplasia type 1 (MEN1) syndrome, genetically confirmed. A unique case of MEN1 syndrome was identified, involving multiple malignancies: papillary thyroid carcinoma, tonsillar squamous cell carcinoma, a pancreatic grade 1 NET, an atypical thymic carcinoid and a lung adenocarcinoma. This case highlighted a large heterozygous deletion in the MEN1 gene (exons 3–8), suggesting a possible pathogenic variant contributing to the disease’s course. The impact of a second neoplasm on the disease progression was less significant compared to the influence of NETs.

Conclusions: Patients with NETs exhibit an incresed risk of developing SPM, with potential genetic syndromes like MEN1 playing a pivotal role in predisposing individuals to multiple neoplasms. Furthermore, the diagnosis of SPMs both prior to and following NET detection emphasizes the importance of vigilant, ongoing surveillance in this patient population. The progression of NETs rather than SPMs was the dominant determinant of patient outcomes, suggesting a unique dynamic that warrants further investigation.