The Neuroendocrine System
Together, the nervous and endocrine systems make up the neuroendocrine system.
The human nervous system is made up of the central nervous system (CNS) including the brain and spinal cord and the peripheral nervous system (PNS), a complex network of nerves and cells that carry messages to and from the CNS and various parts of the human body.
The endocrine system is the collection of glands within the human body. These glands are responsible for producing hormones that control and regulate various processes including digestion, reproduction, cellular metabolism and heart rate. The glands of the endocrine system are:
- Pancreas
- Hypothalamus
- Thyroid
- Parathyroid
- Pituitary Gland
- Adrenal Gland
- Ovaries and Testes
The CNS send signals through the PNS to the different parts of the body, including the glands of the endocrine system. These messages control various functions, regulate the body and maintain homeostasis through signaling the production of hormones by glands within the endocrine system.
Neuroendocrine Tumors
Neuroendocrine Tumors (NETs) are tumors that originate in neuroendocrine cells or cells that produce hormones in response to signals from the nervous system. These cells are responsible for performing functions in the body such as regulating the movement of air and blood through the lungs and how quickly food is processed through the gastrointestinal tract. The presence of these tumors can cause a disruption in the production of the hormones in the affected area(s) thereby affecting how the body performs these tasks.
NETs are considered rare tumors although the incidence of NETs has continued to increase over the course of the last 10-15 years with approximately 12,000 patients being diagnosed in the United States each year. Due in part to the rarity of the disease, NETs are often misdiagnosed and the correct diagnosis usually occurs in the late stages of the illness with approximately 50% of NETs having already spread to other parts of the neuroendocrine system when the diagnosis is made.
NETs can be found anywhere in the body where there are neuroendocrine cells. Some of the more common primary locations are the pancreas (pancreatic NETs or PNETs), the lungs (pulmonary NETs) and the gastrointestinal tract including the stomach, small intestine, small bowel and rectum. Carcinoids are a type of slow-growing NET that is most frequently found in the GI tract. Carcinoids are often diagnosed by chance when the tumor is located during surgery.
NETs can arise spontaneously or can be a result of an inherited disorder. Multiple Endocrine Neoplasias types 1 and 2 (MEN1 and MEN2), pheochromocytoma, paraganglioma and von Hippel-Lindau Disease (VHL) are all examples of neuroendocrine tumors that have a hereditary component. It is important to note that even these NETs are inherited a minority of the time and like other NETs most commonly occur sporadically.
