Comparative Outcomes in Patients With Small- and Large-Cell Neuroendocrine Carcinoma (NEC) and Mixed Neuroendocrine-Non-Neuroendocrine Neoplasm (MiNEN) of the Stomach

Background Gastric neuroendocrine carcinomas (NECs), consisting of both large- and small-cell NECs, and mixed adenoneuroendocrine carcinomas (MANECs), including mixed neuroendocrine-non-neuroendocrine neoplasms (MiNENs), are a group of high-grade malignancies. Few studies to date have reported clinical outcomes, including prognosis, in patients with these tumors. This study therefore evaluated the clinicopathologic outcomes and prognosis in patients with NECs and MANECs. Methods This study included 36 patients diagnosed with gastric NECs, including 23 with large-cell and 13 with small-cell NECs, and 85 with MiNENs, including 70 with high-grade and 15 with intermediate-grade MiNENs. Clinical outcomes, including overall survival (OS) and disease-free survival (DFS), were assessed. Results DFS was significantly poorer in patients with NEC than in patients with intermediate-grade MiNEN (P < .05), whereas both OS and DFS were similar in patients with NEC and high-grade MiNEN (P > .05). Patients with large-cell NEC were more likely to undergo aggressive surgery than patients with high-grade MiNEN (P < .05). Lymphovascular invasion was more frequent and DFS poorer in patients with large-cell than small-cell NECs (P < .05 each). Conclusion DFS is significantly poorer in patients with NEC than in patients with intermediate-grade MiNEN and significantly lower in patients with large-cell than small-cell NECs.