Gastric neuroendocrine neoplasms: analysis of a cohort of patients followed at the Brazilian National Cancer Institute.

Objective: Gastric neuroendocrine neoplasms (G-NENs) are rare tumors categorized into subtypes, each exhibiting unique characteristics, levels of aggressiveness and prognostic implications. This study aimed to describe the experience on G-NEN management at the Brazilian National Cancer Institute.

Methods: Retrospective analysis involving all patients diagnosed with G-NEN from July 2000 to October 2022.

Results: 116 patients with G-NEN were identified; histopathological classification was possible in only 97 patients. Of these, 85 (87.6%) cases were of gastric neuroendocrine tumors (G-NETs) and 12 (12.4%) cases were of gastric neuroendocrine carcinoma (NEC). According to the WHO classification, 51 were classified as NET-G1, 31 as NET-G2, three as NET-G3 and 12 as NEC. Among the G-NETs, type 1 was most prevalent with 60 cases, followed by type 3 (eleven cases) and type 2 (five cases). Nonmetastatic patients were initially treated with endoscopic resection (59 patients), endoscopic surveillance (18 patients) and upfront surgical intervention (18 patients). For metastatic cases, treatment regimens included platinum-based chemotherapy, somatostatin analogs, peptide receptor radionuclide therapy and palliative surgical options. The median overall survival was 84.5 months for NET-G1, 73.4 months for NET-G2, 17.4 months for NET-G3 and 6.2 months for NEC.

Conclusion: This report presents the largest cohort of G-NEN in Brazil. While type 1 small G-NET generally exhibits indolent behavior, NEC is characterized by extreme aggressiveness. The survival outcomes observed in this treated population align with those reported in oncology centers from higher-income regions. This underscores the necessity for establishing reference centers dedicated to neuroendocrine tumors in low- to middle-income countries.