Neuroendocrine tumors (NETs) are a rare type of tumor that can make hormones. Hormones are usually made and released by the neuroendocrine system. This system is made up of special tissues and glands. The endocrine tissue is partially controlled by the brain. Hormones affect how the body works. Examples are the metabolic rate, blood flow, or breathing. They can also change the levels of materials in the blood, such as glucose or calcium. NETs are found throughout the body in the cells of the: In many cases, neuroendocrine tumors cannot be identified as a specific type of cancer. When this occurs, it is called neuroendocrine carcinoma. Copyright © Nucleus Medical Media, Inc.Cancer is when cells in the body split without control or order. These cells go on to form a growth or tumor. The term cancer refers to harmful growths. These growths attack nearby tissues. They also spread to other parts of the body. It's not clear exactly what causes these problems. It’s likely a mix of genes and the environment. The chances of NETs depend on the type of cancer. Your chances are higher if you:NETs may produce excess hormones. This can cause certain problems. In those that have them, they will differ based on where the tumor is and what hormones are affected. General symptoms of cancer may include:The doctor will ask about your symptoms and health history. A physical exam will be done. In some cases, a tumor is found while looking for something else. You may have: The physical exam and test results help find the cancer stage. Staging helps guide a treatment plan. NETs are staged from 0-4. Stage 1 is a very localized cancer. Stage 4 is a spread to other parts of the body. The treatment depends on the stage and type of cancer. In most cases, treatments are combined. Some can be used to ease symptoms caused by tumors or hormones that are causing problems. Surgery removes as much of the tumor as possible. If cancer has spread, nearby tissue or lymph nodes are also removed. Surgery may be done with a scope or as an open procedure. Ablation is the use of heat, electricity, ethanol, or radiofrequency waves. This destroys the cancer using a small needle. Sometimes a probe is inserted into the tumor. Radiation therapy is the use of radiation to kill cancer cells and shrink tumors. radiation may be used before surgery to shrink the tumor or after to make sure all the cancer has been removed. Chemotherapy is the use of drugs to kill cancer cells. It may given by mouth, shots, or IV. The drugs enter the bloodstream and travel throughout the body. It also may be used before or after surgery. Medicines are used to:There is no way to prevent NETs since the cause is unknown. American Cancer SocietyNational Cancer InstituteKulke MH, Benson AB 3rd, Bergsland E, et al. Neuroendocrine tumors. J Natl Compr Cancer Netw. 2012;10(6):724-764. Neuroendocrine tumor. Cancer.net website. Available at: http://www.cancer.net/cancer-types/neuroendocrine-tumor. Accessed July 24, 2018. Neuroendocrine tumors. EBSCO DynaMed Plus website. Available at:https://www.dynamed.com/topics/dmp~AN~T576496/Neuroendocrine-tumors. Accessed July 24, 2018. Signs and symptoms of cancer. American Cancer Society website. Available at: https://www.cancer.org/cancer/cancer-basics/signs-and-symptoms-of-cancer.html. Updated August 11, 2014. Accessed July 24, 2018. Warner RR. Enteroendocrine tumors other than carcinoid: A review of clinically significant advances. Gastroenterology. 2005;128(6):1668-1684. Last reviewed May 2018 by EBSCO Medical Review Board Mohei Abouzied, MD, FACP Last Updated: 7/24/2018