Last decade of advances in gastric neuroendocrine tumors: Innovations, challenges, and future directions.

Abstract

Background: Gastric neuroendocrine tumors (G-NETs) are rare tumors originating from enterochromaffin-like cells, with an incidence of 0.4 per 100000 annually. There are three main types: (1) Type I, linked to chronic atrophic gastritis and hypergastrinemia, makes up 75%-80% of G-NETs; (2) Type II, associated with Zollinger-Ellison syndrome (ZES) and multiple endocrine neoplasia, comprises 5%; and (3) Type III, sporadic tumors with a higher metastatic potential, accounting for 15%-25%. Diagnosis involves endoscopy, biopsy, and histological examination. Additional methods include serum gastrin testing, immunohistochemistry, and imaging techniques such as computer tomography or magnetic resonance imaging for detecting metastasis. Type I treatment usually involves endoscopic resection (ER), with surgical resection for recurrence. Somatostatin analogs (SSAs) can reduce tumor size, and the prognosis is generally excellent. Type II treatment centers on surgical removal of the gastrinoma, with ER for smaller lesions and SSAs for symptom management. Type III requires surgical resection (partial or total gastrectomy) with lymph node dissection, and possibly chemotherapy. This type has a worse prognosis due to its aggressive nature. Emerging treatments like Peptide Receptor Radionuclide Therapy are promising for advanced cases, and ongoing research into immunotherapies is expanding future treatment options. Regular endoscopic follow-up is crucial to monitor for recurrence or metastasis across all types. Our literature review explores the current perspectives on G-NETs and highlights the importance of further research to improve diagnostic precision and treatment, particularly for those associated with less favorable cases.

Aim: To improve diagnostic precision and treatment, particularly for those associated with less favorable cases.

Methods: A systematic search was conducted in PubMed, Scopus, and Web of Science until September 2024. Two independent reviewers screened titles, abstracts, and full texts for eligibility based on G-NET treatment in adults. Eligible studies included cohort studies, clinical trials, case series, and case reports, while in vitro, pediatric, and non-English studies were excluded. Relevant data were extracted independently, and disagreements were resolved through discussion. Study quality was assessed using appropriate tools.

Results: G-NETs are rare, classified into three types: (1) Type I; (2) Type II; and (3) Type III. Type I G-NETs, often associated with chronic atrophic gastritis, are typically slow-growing and low-grade, with favorable outcomes following surgical resection. Type II G-NETs arise in hypergastrinemia conditions like multiple endocrine neoplasia and ZES, showing moderate malignancy risk. Type III G-NETs, the most aggressive and least common, present with distant metastases and poor prognosis. Diagnosis relies on endoscopy, imaging, and biomarkers like chromogranin A. Treatment varies by type, ranging from ER to aggressive surgery and chemotherapy for advanced cases. Regular follow-up is essential to monitor recurrence, particularly for type III G-NETs.

Conclusion: G-NETs require tailored diagnosis and treatment based on type and stage. Types I and II generally have better prognosis, while types III and IV are linked to poorer outcomes due to invasion and metastasis. Treatment strategies vary from ER for type I to extensive surgery for type III. Emerging therapies, like somatostatin analogs and peptide-receptor radionuclide therapies, show promise in advanced cases. Further research is essential to improve early diagnosis and treatment, particularly for high-risk lesions.