What are Neuroendocrine Tumors?

Neuroendocrine tumors are distinctive tumors that can arise in almost any organ in the body. They are recognized because they either produce a hormone or because the cells of the tumor contain small granules (called neuroendocrine granules) that are characteristic of normal cells that produce hormones.Depending on the organ in which they arose and their appearance under the microscope, neuroendocrine tumors are often treated very differently from other cancers in the body. Some neuroendocrine tumors, including the small cell carcinomas, are more aggressive than other neuroendocrine tumors, while other neuroendocrine tumors such as carcinoid tumors, are less aggressive.

Neuroendocrine tumors are important to recognize for three reasons:

1) As hinted at above, neuroendocrine tumors are treated in very specific ways. For example, because many neuroendocrine tumors grow slowly, when technically possible, surgery is often the treatment of choice.

2) Second, many, but again not all, neuroendocrine tumors produce hormones and release these hormones into the blood stream [link to syndromic NET page]. Hormones are chemicals made by cells that can stimulate other cells in the body into action. These hormones produced by neuroendocrine tumors can cause significant symptoms and complications that have to be managed. For example, “insulinoma” is a neuroendocrine tumor of the pancreas that, as the name suggests, releases the hormone insulin into the blood stream. This insulin can act on other cells in the body to greatly lower blood sugar (glucose) levels.

3) Third, many, and again not all, neuroendocrine tumors arise as a part of a genetic predisposition [link to familial page]. For example, individuals with the “multiple endocrine neoplasia, type 1 (MEN 1)” syndrome inherit a genetic change that predisposes them to develop neuroendocrine tumors of the parathyroid glands, pituitary, pancreas and upper gastrointestinal tract. Similarly, individuals with the “multiple endocrine neoplasia, type 2 (MEN 2)” syndrome inherit a genetic change that predisposes them to develop neuroendocrine tumors of the thyroid (called medullary cancer), parathyroid and adrenal glands (called pheochromocytoma). The management of patients with a neuroendocrine tumor therefore includes a good understanding of the role that family cancer history can play in these diseases.