According to the Ki-67 proliferation index and mitotic count, neuroendocrine tumors are classified into well-differentiated neuroendocrine tumors (NET G1, G2, G3), poorly differentiated neuroendocrine carcinomas (NEC), and mixed neuroendocrine-non-neuroendocrine tumors (2). The gene discussed is MKI67; the disease is neuroendocrine carcinoma.