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What Are Neuroendocrine Tumors?

Neuroendocrine tumors are rare cancers that start in neuroendocrine cells. Neuroendocrine cells are specialized cells in the body that are similar to nerve cells and cells that produce hormones. Though they occur most often in the lungs, small intestine, appendix, pancreas, and rectum, neuroendocrine tumors can occur anywhere in the body.

It is estimated that around 12,000 people in the United States are diagnosed with a neuroendocrine tumor each year, and that some 175,000 people in the U.S. are living with a neuroendocrine tumor. The number of people diagnosed with neuroendocrine tumors increases each year, thanks in part to better testing and increased awareness of neuroendocrine tumors.

Neuroendocrine Tumor Prognosis and Survival Rates

The prognosis for neuroendocrine tumors depends on where the cancer is located, what the tumor tissue looks like under a microscope, and the stage at which it is diagnosed. Some neuroendocrine tumors are so rare that there are no accurate survival rates for them, but for pancreatic neuroendocrine tumors in particular, the overall five-year survival rate for all stages of the cancer is 53%, meaning that 47% of patients will die within five years of being diagnosed with neuroendocrine tumors. The five-year survival rate for lung neuroendocrine tumors is 89%, and the five-year survival rate for GI tract neuroendocrine tumors is 94%.

Why Come to the CU Cancer Center for Neuroendocrine Tumors

As the only National Cancer Institute-designated Comprehensive Cancer Center in Colorado and one of only four in the Rocky Mountain region, the University of Colorado Cancer Center has doctors who provide cutting-edge, patient-centered neuroendocrine tumor care, and researchers focused on diagnostic and treatment innovations.  

The CU Cancer Center offers clinical trials for neuroendocrine tumors. These trials offer patients alternatives to traditional cancer treatment and can result in remission or increased life spans.

Types of Neuroendocrine Tumor

Neuroendocrine tumors can form anywhere in the body, but the most common types of neuroendocrine tumors are neuroendocrine tumor of the GI tract, neuroendocrine tumor of the lung, and neuroendocrine tumor of the pancreas. Some neuroendocrine tumors create high levels of hormone-like substances known as neuropeptides and amines. If those substances are released at relatively high levels, the tumor is known as a “functional” neuroendocrine tumor, and it may lead to a group of symptoms known as carcinoid syndrome. When the tumor releases neuropeptides and amines at lower levels, it is known as a “non-functional” neuroendocrine tumor. 

Rare types of neuroendocrine tumors known as pheochromocytoma and paraganglioma can form in the adrenal glands.

Neuroendocrine tumor of the GI tract

Neuroendocrine tumors most often form in the GI tract, usually in the large intestine, small intestine, rectum, and appendix. Neuroendocrine tumors in the GI tract were once called carcinoid tumors.

Neuroendocrine tumor of the lung 

The lungs are the second most common location for neuroendocrine tumors to form. Around 30% of neuroendocrine tumors form in the bronchial system, the system of airways in the lungs. 

Neuroendocrine tumor of the pancreas

Around 7% of neuroendocrine tumors form in the pancreas, a pear-shaped gland located in the abdomen between the stomach and spine. “Functional’ neuroendocrine tumors in the pancreas — those that release higher levels of neuropeptides and amines — are classified into five major types, based on the hormones the cells create under normal circumstances.

  • Gastrinoma. A gastrinoma is a pancreas neuroendocrine tumor that creates too much gastrin, a hormone that causes acid production in the stomach. An overabundance of stomach acid can cause painful ulcers, a condition known as Zollinger-Ellison syndrome.
  • Glucagonoma. A glucagonoma is a pancreas neuroendocrine tumor that makes too much of a hormone called glucagon. Glucagonomas can cause hyperglycemia, an overabundance of sugar in the blood.
  • Insulinoma. An insulinoma creates too much insulin, causing hypoglycemia, or low blood sugar. Insulinomas are more likely than other neuroendocrine tumors to be noncancerous. Only around 10% become cancerous.
  • Somatostatinoma. Somatostatinomas, which typically develop in the head of the pancreas, can create a hormone called somatostatin. Somatostatin controls the production of a number of other hormones, including growth hormone, insulin, and gastrin.
  • VIPoma. A VIPoma begins in the cells of the pancreas that create the hormone vasoactive intestinal peptide (VIP), which helps to move water into the intestines. An overabundance of VIP causes chronic diarrhea, which can lead to a condition known as Verner-Morrison syndrome.

Risk Factors for Neuroendocrine Tumor

Neuroendocrine tumors have multiple risk factors: behaviors or conditions that increase a person’s chances of getting a disease such as cancer. Risk factors for neuroendocrine tumors include:            

Risk factors for neuroendocrine tumors of the GI tract

  • Family history of the inherited genetic syndrome multiple endocrine neoplasia type 1 (MEN1).
  • Race and gender: neuroendocrine tumors of the GI tract are more common in white people than in other ethnic and racial groups. They are slightly more common in women than in men.
  • Age: 55-65 is the typical age range for diagnosis of a neuroendocrine tumor in the GI tract.
  • Other medical conditions: Diseases that damage the stomach and hinder acid production can result in higher risk for neuroendocrine tumors of the GI tract. People with pernicious anemia are also at higher risk. 

Risk factors for neuroendocrine tumors of the lung

  • Family history of the inherited genetic syndrome multiple endocrine neoplasia type 1 (MEN1).
  • Race: neuroendocrine tumors of the lung are more common in white people than in other ethnic and racial groups.
  • Age: 45-55 is the typical age range for diagnosis of a neuroendocrine tumor in the lung.

Risk factors for neuroendocrine tumors of the pancreas

  • Inherited genetic syndromes including multiple endocrine neoplasia type 1 (MEN1), neurofibromatosis type 1 (NF1), and Von Hippel-Lindau syndrome (VHL).
  • Smoking.
  • Alcohol use.
  • Family history of cancer.
  • Diabetes.
  • Chronic pancreatitis, or inflammation of the pancreas.

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Information reviewed by Christopher Lieu, MD, in January 2023.