A neoplasm with neuroendocrine differentiation arising from the digestive system. It includes neuroendocrine tumors (well-differentiated endocrine tumors or carcinoid tumors and well differentiated endocrine carcinomas) and neuroendocrine carcinomas (poorly differentiated neuroendocrine carcinomas, small cell carcinomas, and large cell neuroendocrine carcinomas). The disease is Monarch Disease Ontology entry MONDO_0024503 (digestive system neuroendocrine neoplasm). Also known as: alimentary part of gastrointestinal system NET, alimentary part of gastrointestinal system neuroendocrine neoplasm, alimentary part of gastrointestinal system neuroendocrine tumor, alimentary part of gastrointestinal system neuroendocrine tumor, well differentiated, low or intermediate grade, alimentary part of gastrointestinal system neuroendocrine tumour, carcinoid tumor of digestive system, carcinoid tumour of digestive system, digestive system NET.