• Neuroendocrine neoplasm (NENs) are divided into neuroendocrine tumors (NETs) and neuroendocrine carcinomas (NECs). These are rare malignancies occurring for example in the gastrointestinal tract, islets of the pancreas, lung, adrenal medulla, thyroid C-cells, etc. and are heterogeneous group of neoplasms with unique tumor biology, natural history, and clinical management issues.
• Their incidence has increased over the last decade, with an incidence of 6 per 100,000 persons a year and they represent 0.46% of all malignancies.
• Most NETs are sporadic, but they can be part of familial cancer syndromes such as multiple endocrine neoplasia type 1 (MEN1), neurofibromatosis type 1 (NF1) or Von Hippel- Lindau (VHL) syndrome. Whereas poorly differentiated neuroendocrine carcinomas (NECs) are all high-grade carcinomas that resemble small cell carcinoma or large cell carcinoma of the lung.
• Treatment for localized NETs is surgical resection, however, a variety of therapeutic options are available for patients with advanced NETs. When to apply a given option, what combination therapeutic approach should be used, how long treatment should be continued should be used is unclear and controversial. Objective

-Characterize the natural history of neuroendocrine neoplasms (NENs). Data will include clinical presentation, patterns of disease progression, response or lack of response to therapeutic interventions, disease recurrence and overall survival.

• Subjects with confirmed or suspicion of NENs.
• Age greater than or equal to 3 years old

• This protocol is a subprotocol of protocol 19C0016 Natural History and Biospecimen Accrual Study for Children and Adults with Rare Solid Tumors . After enrollment on the master protocol and undergoing evaluations detailed in the master protocol, patients will be enrolled on this subprotocol specific for NENs.
• Medical histories will be documented, and patients followed throughout the course of their illnesses, with particular attention to patterns of disease recurrence and progression, response to therapies, duration of responses and hormone production in patients with hormone production as a manifestation of their disease. Tumor growth rates will also be calculated throughout the course of the disease.