National Center for Advancing and Translational Sciences Genetic and Rare Diseases Information Center, a program of the National Center for Advancing and Translational Sciences

Neuroendocrine tumor

A neuroendocrine tumor (NET) is a rare type of tumor that arises from specialized body cells called neuroendocrine cells. These cells have traits of both nerve cells and hormone-producing cells, and release hormones into the blood in response to signals from the nervous system.[1][2] Because a neuroendocrine tumor arises from cells that produce hormones, the tumor can also produce hormones.[2]

Neuroendocrine tumors can develop anywhere in the body, but most occur in the digestive tract, pancreas, rectum, lungs, or appendix.[1][2][3] They can be non-cancerous (benign) or cancerous (malignant).[1] They usually grow slowly over many years, but there are fast-growing forms.[2][4]

There are many types of neuroendocrine tumors, but most are classified as one of two main types:[2][3]
  • Carcinoid tumors - NETs that most commonly arise in the digestive tract, lungs, appendix or thymus. They can also grow in the lymph nodes, brain, bone, gonads (ovaries and testes) or skin.[2][5]
  • Pancreatic neuroendocrine tumors (also called islet cell tumors) - NETs that typically arise in the pancreas, although they can occur outside the pancreas.[6]

A pheochromocytoma is another, rarer type of NET that usually develops in the adrenal gland, but can also arise in other parts of the body.[2]

Signs and symptoms depend on the tumor's type, size and location; whether it produces hormones; and whether it has spread to other parts of the body (metastasized).[2] NETs are typically described as functional or nonfunctional. Functional NETs produce a specific set of symptoms due to the production of excess hormones, while non-functional NETs generally do not cause specific symptoms. In many cases, a person has no symptoms until the tumor spreads to the liver and/or impairs the function of an organ or system. This can make NETs very hard to diagnose.[7]

The majority of NETs are not inherited and occur sporadically in people with no family history of NETs.[3] However, some NETs are associated with a hereditary cancer or tumor syndrome such as multiple endocrine neoplasia type 1 (most commonly), Von Hippel-Lindau disease, tuberous sclerosis, or neurofibromatosis type 1 (NF1). Inheritance of each of these is autosomal dominant.[3]

Treatment of NETs depends on many factors such as the tumor's type, location, aggressiveness, and hormone-producing capabilities; as well as whether it has metastasized.[1] Management options may include surveillance, surgery to remove the tumor and/or surrounding tissue, and various non-surgical therapies to shrink the tumor, stop it from growing, or manage symptoms.[8][9][10]

Last updated: 4/25/2019

Making a diagnosis for a genetic or rare disease can often be challenging. Healthcare professionals typically look at a person’s medical history, symptoms, physical exam, and laboratory test results in order to make a diagnosis. The following resources provide information relating to diagnosis and testing for this condition. If you have questions about getting a diagnosis, you should contact a healthcare professional.

Testing Resources

  • The Genetic Testing Registry (GTR) provides information about the genetic tests for this condition. The intended audience for the GTR is health care providers and researchers. Patients and consumers with specific questions about a genetic test should contact a health care provider or a genetics professional.

The resources below provide information about treatment options for this condition. If you have questions about which treatment is right for you, talk to your healthcare professional.

Management Guidelines

  • The North American Neuroendocrine Tumor Society has published several consensus guidelines relating to the medical treatment and management of neuroendocrine tumors. Guidelines are developed pursuant to National Institute of Health (NIH) standards and serve as important references for practicing physicians.

If you need medical advice, you can look for doctors or other healthcare professionals who have experience with this disease. You may find these specialists through advocacy organizations, clinical trials, or articles published in medical journals. You may also want to contact a university or tertiary medical center in your area, because these centers tend to see more complex cases and have the latest technology and treatments.

If you can’t find a specialist in your local area, try contacting national or international specialists. They may be able to refer you to someone they know through conferences or research efforts. Some specialists may be willing to consult with you or your local doctors over the phone or by email if you can't travel to them for care.

You can find more tips in our guide, How to Find a Disease Specialist. We also encourage you to explore the rest of this page to find resources that can help you find specialists.

Healthcare Resources

  • The Neuroendocrine Tumor Research Foundation has a Doctor Database for help finding a physician specializing in treating neuroendocrine tumors. They also provide a link to a list of multidisciplinary diagnosis and treatment centers on the same web page.

Related diseases are conditions that have similar signs and symptoms. A health care provider may consider these conditions in the table below when making a diagnosis. Please note that the table may not include all the possible conditions related to this disease.

Conditions with similar signs and symptoms from Orphanet
This syndrome should be distinguished from a metastatic extension, a combination of sporadic tumours, or a non-inherited multiple form of NETs.
Visit the Orphanet disease page for more information.

Research helps us better understand diseases and can lead to advances in diagnosis and treatment. This section provides resources to help you learn about medical research and ways to get involved.

Clinical Research Resources

  • ClinicalTrials.gov lists trials that are related to Neuroendocrine tumor. Click on the link to go to ClinicalTrials.gov to read descriptions of these studies.

    Please note: Studies listed on the ClinicalTrials.gov website are listed for informational purposes only; being listed does not reflect an endorsement by GARD or the NIH. We strongly recommend that you talk with a trusted healthcare provider before choosing to participate in any clinical study.

General Clinical Trials & Research

  • The Neuroendocrine Tumor Research Foundation is a non-profit organization to support neuroendocrine tumor (NET) research. Their mission is to accelerate scientific discovery that will help create new and more effective therapies for NETs. Each year they seek and fund basic, translational and clinical research proposals with the potential to further understanding of NETs and accelerate the development of diagnostic and therapeutic interventions for patients.

Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

Organizations Supporting this Disease

These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

Where to Start

In-Depth Information

  • Medscape Reference provides information on this topic. You may need to register to view the medical textbook, but registration is free.
  • Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.

Questions sent to GARD may be posted here if the information could be helpful to others. We remove all identifying information when posting a question to protect your privacy. If you do not want your question posted, please let us know.

  1. Neuroendocrine Tumors. Mayo Clinic. August 18, 2017; https://www.mayoclinic.org/diseases-conditions/neuroendocrine-tumors/symptoms-causes/syc-20354132.
  2. Neuroendocrine Tumor: Introduction. Cancer.Net, American Society of Clinical Oncology. November, 2016; https://www.cancer.net/cancer-types/neuroendocrine-tumor/introduction.
  3. Background: Neuroendocrine tumor/carcinoid tumor features. American Association of Endocrine Surgeons. http://endocrinediseases.org/neuroendocrine/neuroendocrine_background.shtml. Accessed 4/30/2018.
  4. Newly Diagnosed: The Basics. The Carcinoid Cancer Foundation. http://www.carcinoid.org/for-patients/diagnosis/newly-diagnosed-the-basics/. Accessed 2/13/2018.
  5. Carcinoid Tumor. Cancer.Net, American Society of Clinical Oncology. August, 2016; https://www.cancer.net/cancer-types/carcinoid-tumor/introduction.
  6. Pancreatic Neuroendocrine Tumors (Islet Cell Tumors) Treatment (PDQ®)–Patient Version. National Cancer Institute. March 22, 2018; https://www.cancer.gov/types/pancreatic/patient/pnet-treatment-pdq.
  7. Pancreatic Neuroendocrine Tumors. Neuroendocrine Tumor Research Foundation (NETRF). https://netrf.org/about-neuroendocrine-tumors/net-tests-treatments/common-neuroendocrine-tumor-sites/understanding-pancreatic-nets/. Accessed 4/25/2019.
  8. Neuroendocrine Tumor: Treatment Options. Cancer.Net (American Society of Clinical Oncology). November, 2016; https://www.cancer.net/cancer-types/neuroendocrine-tumor/treatment-options.
  9. Surgery. Neuroendocrine Tumor Research Foundation (NETRF). https://netrf.org/about-neuroendocrine-tumors/net-tests-treatments/net-treatment-options/net-surgery-options/. Accessed 4/25/2019.
  10. Interventional Radiology as a Treatment for Neuroendocrine Tumors. Neuroendocrine Tumor Research Foundation (NETRF). https://netrf.org/about-neuroendocrine-tumors/net-tests-treatments/net-treatment-options/interventional-radiology/. Accessed 4/25/2019.