Definition of Neuroendocrine tumors
Your neuroendocrine system has cells that have traits similar to nerve cells and to hormone-producing cells of your endocrine glands. These cells are distributed throughout your body within certain organs. Neuroendocrine cells can develop into tumors, many of which grow slowly and others that can be very aggressive and spread to other parts of your body (metastasize).
Neuroendocrine tumors are rare and develop most commonly in the lungs, appendix, small intestine (duodenum), rectum and pancreas. Most neuroendocrine tumors start in the digestive tract, as it has more neuroendocrine cells than any other part of your body. Symptoms and treatment depend on the type of tumor, including where it grows, whether it produces excess hormones, how aggressive it is and whether it has spread.