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Neuroendocrine tumors (NETs)

This page was reviewed under our medical and editorial policy by Maurie Markman, MD, President, Medicine & Science

This page was updated on August 29, 2022.

Neuroendocrine tumors (NETs) form in cells that interact with the nervous system or in glands that produce hormones. These cells, called neuroendocrine cells, can be found anywhere in the body, but NETs are most often found in the abdomen, especially in the gastrointestinal tract. These tumors may also be found in the lungs, pancreas and adrenal glands. Merkel cell cancer, a type of skin cancer, is also categorized as a neuroendocrine cancer.

All NETs are considered malignant (cancerous) tumors. Most NETs take years to develop and grow slowly. However, some NETs may be fast-growing.

More than 12,000 NETs are diagnosed each year in the United States, accounting for a small fraction of the number of new cancer cases. But more and more Americans are being diagnosed with the disease, with incidence rates rising markedly over the past 15 years.

No neuroendocrine tumor patient is the same. Get personalized treatment.

In addition to being rare, NETs are complex and may be difficult to diagnose. In fact, most people aren’t diagnosed with a neuroendocrine tumor until they’ve already experienced symptoms for more than four years. This type of delay can be frustrating. That’s why it’s important to seek care from trained oncologists with expertise in neuroendocrine tumor diagnoses and treatments. At City of Hope, our multidisciplinary team of cancer experts has training and experience in diagnosing and treating all stages of neuroendocrine tumors.

Neuroendocrine tumors are such an important focus at City of Hope that each of our hospitals has a GI Cancer Center dedicated to treating patients with all stages of gastrointestinal diseases. Our gastroenterologists and oncologists understand the complexities of neuroendocrine tumors.

They work with you to create an individualized treatment plan that includes evidence-based treatments and technologies to fight neuroendocrine cancer, combined with supportive care services to help reduce side effects and keep you strong in body, mind and spirit.

This overview will cover the basic facts about neuroendocrine tumors, including:

If you believe you may be experiencing symptoms of neuroendocrine cancer and want to schedule an appointment for diagnostic testing, or if you’re interested in a second opinion on your neuroendocrine tumor diagnosis and treatment plan, call us or chat online with a member of our team.

What causes NETs?

Who gets NETs?

Statistically, whites are more likely to develop an NET than other ethnic groups. Also, for unknown reasons, NETs are slightly more common in women than in men.

Rosie Painter

Rosie P.

Colorectal Cancer

"We called the toll-free number to inquire about a second opinion. Even from that first phone call, I felt well cared for. There were no voice prompts to wade through or shuttling from one person to the next. After meeting with the care team, I had a CT scan and was walked through a proposed treatment plan a day or so later. "


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NET types

NETs can begin in any part of the body, including the:

  • Lungs
  • Gastrointestinal tract (stomach, pancreas, appendix, intestines, colon and rectum)
  • Thyroid gland
  • Adrenal gland
  • Pituitary gland

Doctors may classify a NET tumor by its site of origin, such as GI NET, pancreatic NET or lung NET. NET tumors are almost always considered to be malignant or cancerous.

Learn more about types of neuroendocrine tumors

NET symptoms and signs

NET stages

Staging is a way of describing where the tumor is located, if or where it has spread, and whether it is affecting other parts of the body. Neuroendocrine tumor staging is key in developing the appropriate treatment plan. Diagnostic testing is used by doctors to determine the stage of a NET tumor and to better predict a patient’s prognosis. There are different stage descriptions for different types of NETs.

NETs may:

  • Be contained in a particular area of the body (localized)
  • Have spread to nearby tissues or lymph nodes (regional)
  • Have spread throughout the body (metastatic)

The World Health Organization (WHO) classifies neuroendocrine tumors according to the malignant potential of the tumor:

  • Well-differentiated neuroendocrine tumors (grade 1 and 2)
  • Poorly differentiated neuroendocrine tumors (grade 3)

NETs of the GI tract and pancreas have their own staging systems based on the location and characteristics of the tumor. Some NETs use the staging system for other cancers. For example, the staging of a lung NET is the same as the staging of non-small cell lung cancer. These staging systems are created by the American Joint Committee on Cancer (AJCC).

Learn more about stages of neuroendocrine tumors

Diagnosing NETs

Treating NETs

Neuroendocrine tumor treatment options include:

  • Surgery: Minimally invasive procedures using laparoscopy or laparotomy, either to remove the entire tumor or to reduce its mass if it cannot be completely removed, may be recommended. Mesenteric resections for small bowel tumors and cytoreductive surgery may be recommended for advanced-stage disease.
  • Immunotherapy: These treatments use the drug interferon, which helps stimulate the immune system.
  • Targeted therapy: These drugs attack certain areas of the cancer cell or its environment (including genes and proteins) that may be responsible for the tumor’s growth.
  • Chemotherapy: These drugs are designed to interfere with the growth of cancer cells in order to destroy them.
  • Interventional radiology: This field of medicine uses both catheter- and needle-based therapies.
  • Peptide receptor radionuclide therapy: PRRT therapy combines a cell-targeting protein (or peptide) with a radionuclide (or radioactive material), given intravenously to deliver a high dose of radiation to the tumors.

Learn more about treatment options for neuroendocrine tumors

Diagnosis and treatment options at our City of Hope GI Cancer Centers