High neuroendocrine component is a factor for poor prognosis in gastrointestinal high-grade malignant mixed adenoneuroendocrine neoplasms

Background: High-grade malignant mixed adenoneuroendocrine carcinoma (MANEC) is a highly malignant combined neoplasm formed by an adenocarcinomatous component and a poorly differentiated (Grade 3) neuroendocrine (NE) carcinoma. Methods: Tumors from 21 patients with gastrointestinal high-grade malignant MANECs or tumors with varying percentages of Grade 3 NE component were examined, and the NE component was confirmed by morphological analysis and immunohistochemical staining. Patients were divided into high NE (NE component > 50% in the primary tumor) and low NE (NE component ? 50% in the primary tumor) component groups. Results: High NE component was a poor prognostic factor for patients with high grade MANEC (p=0.021). Out of 13 patients with high-grade malignant MANEC, eight had a pure NE component, one had a pure adenocarcinomatous component, and four had mixed-type cancer in the metastatic lymph nodes. We further enrolled eight patients who had a Grade 3 NE component in the primary tumor and found that the pure NE component in tumor emboli and distant liver metastases were more frequent in the high NE than in the low NE component group (p=0.012 and p=0.046, respectively). Conclusion: The predominant tumor component in primary tumors was a prognostic factor and could predict tumor emboli and liver metastases pathology in high-grade malignant MANECs. ? 2015.