Neuroendocrine Tumor

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.

Symptoms of Neuroendocrine Tumor

Neuroendocrine tumors often do not cause symptoms in their early stages. They are typically discovered during unrelated surgeries or imaging for other conditions. When symptoms are present, the area should be evaluated as soon as possible. 

Carcinoid syndrome

Carcinoid syndrome is a group of symptoms associated with all types of neuroendocrine tumors. Those symptoms include:

  • Facial flushing — redness and a warm feeling in the face.
  • Diarrhea.
  • Sweating.
  • Shortness of breath.
  • Wheezing or other asthma-like symptoms.
  • Weakness.
  • Rapid heartbeat.
  • Heart murmur.
  • High blood pressure or pronounced fluctuations in blood pressure.
  • Scarring of the heart valves, known as carcinoid heart disease.

Other symptoms of neuroendocrine tumors of the GI tract

  • Abdominal pain.
  • Rash.
  • Bright red blood in the stool or tarry, dark stool.
  • Scaly sores on the skin.
  • Mental confusion.
  • Constipation.
  • Nausea and vomiting.
  • Unexplained weight loss.
  • Jaundice — yellowing of the skin and the whites of the eyes.
  • Fatigue. 

Other symptoms of neuroendocrine tumors of the lung

  • Coughing.
  • Bloody phlegm.
  • Pneumonia.
  • Chest pain.

Other symptoms of neuroendocrine tumors of the pancreas

  • Abdominal pain.
  • Jaundice — yellowing of the skin and the whites of the eyes.
  • Vomiting blood.
  • Sweating.
  • Anxiety.
  • Rapid heart rate.
  • Convulsions.
  • Headache.
  • Cloudy vision.
  • Losing consciousness.
  • Inflamed tongue or mouth.
  • Unexplained weight loss.
  • Lump or mass in the abdomen.
  • Hypoglycemia (sign of an insulinoma).
  • Confusion.
  • Ulcers (sign of a gastrinoma).
  • Diarrhea (sign of a gastrinoma).
  • Hyperglycemia (sign of a glucagonoma).
  • Rash on the face, abdomen, or lower extremities (sign of a glucagonoma).
  • Blood clots (sign of a glucagonoma).
  • Watery diarrhea (sign of a VIPoma).
  • Low potassium in the blood (sign of a VIPoma).
  • Digestive problems (sign of a VIPoma).
  • Flushing on the face, chest, or neck (sign of a VIPoma).
  • Fatigue (sign of a VIPoma).
  • Nausea (sign of a VIPoma).
  • Type 2 diabetes (sign of a somatostatinoma).
  • Gallstones (sign of a somatostatinoma). 

Screening for Neuroendocrine Tumor 

Screening is used to look for cancer before a person shows any symptoms of the disease. There are no standard screenings for neuroendocrine tumors, but unusual symptoms should be evaluated by a doctor as soon as possible.

 

Diagnosing Neuroendocrine Tumor 

Based on a patient’s symptoms and after an initial physical examination, a doctor may order certain tests to determine whether the patient has a neuroendocrine tumor. Though testing procedures can vary based on the type of neuroendocrine tumor the doctor is looking for, common screenings for neuroendocrine tumors include:

Biopsy: During a biopsy, a doctor extracts a sample of tissue from the suspected tumor. This is sent to a laboratory for analysis by a pathologist to determine whether the cells in the sample are cancerous.  

Magnetic resonance imaging (MRI): An MRI uses radio waves and magnetic fields to produce detailed images of the body. MRI scans can show if cancer has spread to other sites in the body and if so, how far.

Computed tomography (CT or CAT) scan: A CT scan uses x-rays to take detailed images of the body and can help determine if cancer has spread to other organs or come back after treatment.

Positron emission tomography (PET/DOTATATE) scan: A slightly radioactive form of sugar is injected into the blood, where it is taken in by cells in the body. Since cancer cells grow faster than normal cells, they take in larger amounts of the sugar. Doctors use PET and DOTATATE scans to look for possible areas of cancer spread, and to determine if suspicious areas seen in other imaging tests are cancer or not. 

Endoscopic Ultrasound: This imaging test uses sound waves to create pictures of internal organs or masses. In an endoscopic ultrasound, the imaging device is attached to a fiberoptic scope that can examine the esophagus, stomach, and small intestine. Ultrasound can be used to look for enlarged lymph nodes or a mass inside the lung, stomach, pancreas, or other organs.

Bronchoscopy: A procedure during which a scope is passed down the throat into the bronchi to look for tumors or blockages in the larger areas of the lungs. Biopsies may be taken during this procedure.

Stages of Neuroendocrine Tumor

After diagnosing the presence of a neuroendocrine tumor, the doctor will identify the stage of the disease. The stage is determined by several factors, including where exactly the disease has formed, how extensive it is, and whether and how much it has spread. 

Many of the same tests used to diagnose neuroendocrine tumors are also used to identify the stage, including biopsies, x-rays, CT/CAT scans, PET scans, and ultrasounds.

Doctors typically use the TNM system to determine the stage of a neuroendocrine tumor. The TNM system assesses the size and extent of the tumor (T) and whether it has ulcerated; whether the cancer has spread to nearby lymph nodes (N); and the presence and extent of metastasis (M) to distant lymph nodes, bones, and organs.

After the TNM assessment, the doctor will assign an overall stage number from I to IV, which can be further broken down based on the size of the original tumor and the extent to which the cancer has spread. In general, the lower the stage, the better the prognosis and treatment options.

Neuroendocrine Tumor of the GI Tract Stages

Stomach

Stage I: There is a small tumor that has not spread elsewhere in the body. 

Stage II: The tumor is larger and has grown as far as the subserosa, a layer of tissue that sits behind the layer of muscle in the stomach. The cancer has not spread to the lymph nodes or other sites in the body.

Stage III: The tumor is any size, and the cancer has spread to regional lymph nodes; or the tumor has spread to the outside of the stomach, but the cancer has not spread to the lymph nodes or elsewhere.

Stage IV: The cancer has spread to distant sites in the body.

Duodenum and ampulla of Vater (small intestine) 

Stage I: There is a small tumor that has not spread elsewhere in the body.

Stage II: The tumor is larger than 1 centimeter or has grown as far as the pancreas. The cancer has not spread to the lymph nodes or other sites in the body. 

Stage III: The tumor is any size, and the cancer has spread to regional lymph nodes; or the tumor has spread to the peritoneum or other organs, but the cancer has not spread to the lymph nodes or other sites in the body.

Stage IV: The cancer has spread to distant sites in the body.

Jejunum and ileum (small intestine) 

Stage I: There is a small tumor that has not spread elsewhere in the body.

Stage II: The tumor is larger than 1 centimeter and has grown as far as the subserosa, the layer of tissue that sits behind the layer of muscle in the small intestine. The cancer has not spread to the lymph nodes or other sites in the body.

Stage III: The tumor is any size, and the cancer has spread to regional lymph nodes; or the tumor has spread to the peritoneum or to other organs or structures, but the cancer has not spread to the lymph nodes or other sites in the body.

Stage IV: The cancer has spread to distant sites in the body.

Appendix 

Stage I: The tumor is 2 centimeters or smaller and has not spread to other sites in the body.

Stage II: The tumor is larger than 2 centimeters and has grown as far as the membrane that connects the appendix to the abdomen wall. The cancer has not spread to the lymph nodes or other sites in the body. 

Stage III: The tumor is any size, and the cancer has spread to regional lymph nodes; or the tumor has spread to the peritoneum or beyond, but the cancer has not spread to the lymph nodes or other sites in the body.

Stage IV: The cancer has spread to distant sites in the body.

Colon and rectum

Stage I: The tumor is 2 centimeters or less and has not spread to other sites in the body.

Stage IIA: The tumor has grown into the muscle; or the tumor is larger than 2 centimeters and has invaded the lamina propria or submucosa (thin layers of connective tissue). The cancer has not spread to other sites in the body. 

Stage IIB: The tumor has spread through the muscle and into the subserosal tissue behind it. The cancer has not spread to the lymph nodes or other sites in the body.

Stage IIIA: The tumor has spread to the peritoneum or has invaded nearby organs or structures, but the cancer has not spread to the lymph nodes or other sites in the body.

Stage IIIB: The tumor is any size, and the cancer has spread to regional lymph nodes.

Stage IV: The cancer has spread to distant sites in the body.

Neuroendocrine Tumor of the Lung Stages

Stage 0: Also known as “in situ,” or “in place,” a stage 0 tumor has not grown into nearby tissues or spread outside the lung. A stage 0 tumor is noninvasive.

Stage IA: The tumor is 3 centimeters or smaller and has not spread to any lymph nodes. 

Stage IB: The tumor is between 3 and 4 centimeters and has not spread to any lymph nodes.  

Stage IIA: The tumor is between 4 and 5 centimeters and has not spread to any lymph nodes.

Stage IIB: The tumor is 5 centimeters or smaller and has spread to the lymph nodes; or the tumor is larger than 5 centimeters and has not spread to the lymph nodes.

Stage III: Cancer has spread to the lymph nodes but not to distant sites in the body.

Stage IV: The cancer has spread to the opposite lung, the fluid surrounding the lung or the heart, or distant parts of the body.

Neuroendocrine Tumor of the Pancreas Stages 

Stage I: The tumor is small and has not spread to other sites in the body.

Stage II: The tumor is larger and has not spread to the regional lymph nodes or other sites in the body.

Stage III: The tumor is any size and has spread to the regional lymph nodes; or the tumor has spread to the stomach, spleen, colon, or adrenal gland, or the wall of the celiac axis or the superior mesenteric artery, but the cancer has not spread to the regional lymph nodes or any other sites in the body.

Stage IV: The cancer has spread to distant sites in the body.

 

Treatments for Neuroendocrine Tumor

The treatment for neuroendocrine tumor is customized to each patient and depends on the stage at which the patient is diagnosed, and the patient’s general health.  

Neuroendocrine tumor care teams may include multiple health care specialists, including primary care providers, gastroenterologists, endocrinologists, medical oncologists, hematologists, and radiation oncologists, as well as nurse practitioners, physician assistants, nurses, psychologists, social workers, and rehabilitation specialists. CU Cancer Center doctors offer specialized care for patients with neuroendocrine tumors. 

Treatments for neuroendocrine tumor include surgery, radiation therapy, chemotherapy, immunotherapy, targeted drug therapy, somatostatin analogs, and peptide receptor radionuclide therapy. Patients may receive one or more of these treatments in combination. Some patients may also be eligible to participate in clinical trials — doctor-led research studies of new or experimental procedures or treatments.

Surgery for Neuroendocrine Tumor

Surgery for neuroendocrine tumor involves removing the entire tumor, as well as a small amount of surrounding healthy tissue. Surgery is the most common treatment for a neuroendocrine tumor. 

Radiation Therapy for Neuroendocrine Tumor

Radiation therapy uses high-powered energy to kill cancer cells. A doctor who specializes in radiation therapy to treat cancer is a radiation oncologist. The primary type of radiation therapy used to treat neuroendocrine tumors is external beam radiation, which uses a machine located outside the body to focus a beam of X-rays on the area of the body where the cancer is located. 

Chemotherapy for Neuroendocrine Tumor

Chemotherapy uses drugs to kill rapidly growing cancer cells. Drugs are either injected into a vein or taken orally. Depending on the type of neuroendocrine tumor, chemotherapy may be combined with immunotherapy or followed by radiation therapy. 

Immunotherapy for Neuroendocrine Tumor

Sometimes the body’s immune system does not attack cancer because cancer cells produce proteins that help them hide from immune system cells. Immunotherapy, also called biologic therapy, boosts the patient’s immune system to help it attack and destroy cancer cells.

Targeted Drug Therapy for Neuroendocrine Tumor

Targeted therapy focuses on the specific genes, proteins, or tissue environments that contribute to neuroendocrine tumors, limiting damage to non-cancerous cells and tissues.  

Somatostatin Analogs for Neuroendocrine Tumor

A hormone in the body called somatostatin controls the release of other hormones, including insulin and glucagon. Somatostatin analogs are synthetic forms of somatostatin that are used to control the symptoms that are created when a neuroendocrine tumor releases specific hormones into the body.

Peptide Receptor Radionuclide Therapy for Neuroendocrine Tumor

Peptide receptor radionuclide therapy involves the use of a radioactive drug that works by binding to somatostatin receptors on tumor cells. The drug then enters the cell, allowing radiation to attack the tumor. 

The University of Colorado (CU) Cancer Center partners with UCHealth, Children’s Hospital Colorado, and Rocky Mountain Regional VA to provide clinical care. Please make an appointment with one of our clinical partners to be seen by a CU Cancer Center doctor.


UCHealth:

UCHealth Cancer Care - Anschutz Medical Campus
1665 Aurora Court Anschutz Cancer Pavilion
Aurora, CO 80045
720-848-0300

UCHealth Cherry Creek Medical Center
100 Cook Street
Denver, CO 80206
720-848-0000

UCHealth Cancer Center - Highlands Ranch
1500 Park Central Drive
Highlands Ranch, CO 80129
720-516-1100

UCHealth Lone Tree Medical Center
9548 Park Meadows Drive
Lone Tree, CO 80124
720-848-2200


Children's Hospital Colorado:
13123 East 16th Avenue
Aurora, CO 80045
720-777-6740


Rocky Mountain Regional VA Medical Center:
1700 North Wheeling Street
Aurora, CO 80045-7211
303-399-8020


 

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