Mixed neuroendocrine non-neuroendocrine neoplasms in gastroenteropancreatic tract

Mixed neuroendocrine non-neuroendocrine neoplasms (MiNENs) are a heterogeneous group of malignant neoplasms that can settle in the gastroenteropancreatic tract. They are composed of a neuroendocrine (NE) and a non-NE component in at least 30% of each tumour. The non-NE component can include different histological combinations of glandular, squamous, mucinous and sarcomatoid phenotypes, and one or both of the components can be low-or high grade malignant. Recent changes in the nomenclature of these neoplasms might lead to great deal of confusion, and the lack of specific clinical trials is the main reason why their management is difficult. The review aims to clarify the definition of MiNEN and analyze available evidence about their diagnosis and treatment options according to their location and extension through careful analysis of the available data. It would be important to reach a general consensus on their diagnosis in order to construct a classification that remains stable over time and facilitates the design of clinical trials that, due to their low incidence, will require long recruitment periods.

Digestive System Mixed Neuroendocrine-Non-Neuroendocrine Neoplasms

Mixed neuroendocrine-non-neuroendocrine neoplasms (MiNEN) are a heterogeneous subgroup of rare neoplasms that represent about a third of all poorly differentiated neuroendocrine carcinomas (PDNEC). MiNEN combine a neuroendocrine component, usually a PDNEC, and a non-neuroendocrine component, generally an adenocarcinoma, both accounting for at least 30% of the neoplasm. MiNEN are classified as high-, intermediate-, or low-grade malignancies depending on the metastatic potential of the tumour components. High-grade malignant component should be considered even if it represents <30% of the tumour. The prognosis of MiNEN is generally intermediate between those of the two "pure" components composing it. The aim of this comprehensive review of the literature is to suggest a standardized management of MiNEN. An increasing body of evidence suggests that PDNEC components share molecular abnormalities with their adenocarcinoma counterparts, but also display additional alterations. This advocates for a common origin, and that the presence of a PDNEC component in an adenocarcinoma could indicate a turning point in carcinogenesis.