Neuroendocrine Tumors: Symptoms and Signs

Approved by the Lineagotica Editorial Board, 04/2019

ON THIS PAGE: You will find out more about body changes and other things that can signal a problem that may need medical care. Use the menu to see other pages.

NETs can be discovered for many different reasons because there is no single set of common symptoms. In its early stages, a NET often causes no symptoms and may only be detected during an unrelated x-ray or surgery for another condition. If a person with a NET has symptoms, those symptoms may be associated with the size and/or location of the tumor or with the release of hormones, such as carcinoid syndrome.

If you are concerned about any changes you experience, please talk with your doctor. Your doctor will ask how long and how often you’ve been experiencing the symptom(s), in addition to other questions. This is to help figure out the cause of the problem, called a diagnosis.

Symptoms of a NET

Depending on the type of NET, a person may experience the following tumor-related symptoms or signs:

General cancer symptoms:

  • Fatigue

  • Loss of appetite

  • Unexplained weight loss

Symptoms related to the tumor size and/or location:

  • Persistent pain in a specific area

  • Thickening or a lump in any part of the body

  • Nausea or vomiting

    • A cough or hoarseness that does not go away

    • Changes in bowel or bladder habits

    • Jaundice, which is the yellowing of the skin and whites of the eyes

    • Unusual bleeding or discharge

Symptoms related to the release of hormones:

  • Diarrhea

  • Facial flushing, usually without sweating

  • Hyperglycemia, which is a high level of glucose in the blood. Glucose is a sugar that is converted into energy by the body. Hyperglycemia causes frequent urination, increased thirst, and increased hunger.

  • Hypoglycemia, which is a low level of glucose in the blood. It causes fatigue, nervousness and shakiness, dizziness or light-headedness, sweating, seizures, and fainting.

  • Gastric ulcer disease

  • Skin rash

  • Confusion

  • Anxiety

  • Some people also experience nutritional deficiencies before a diagnosis, such as niacin and protein deficiency. Others develop this symptom later.

For symptoms related to a specific type of NET, visit its individual section (see the Introduction for a list.)

Carcinoid syndrome

Carcinoid syndrome is the classic example of a sign of a functional NET. It occurs most commonly in people with small intestine and lung NETs that have spread to another part of the body, called metastatic. In carcinoid syndrome, serotonin is produced by the tumor and can cause 1 or more of the following symptoms or signs. Serotonin is most easily and reliably measured in the urine, when it gets converted into 5-hydroxyindoleacetic acid (5-HIAA), and it is measured with a 24-hour urine collection test. It is important to note that these symptoms alone are not enough to diagnose carcinoid syndrome. Blood or urine tests to measure for suspected hormones are also needed to make a diagnosis. Not all people with a NET develop carcinoid syndrome.

  • Facial flushing, which is redness and a warm feeling over the face

  • Diarrhea

  • Shortness of breath

  • Wheezing or asthma-like symptoms

  • Unexplained weight gain

  • Weakness

  • Fast heartbeat

  • Heart murmur

  • High blood pressure and significant fluctuations in blood pressure

  • Carcinoid heart disease, which is a scarring of the heart valves caused by serotonin.

Stress, strenuous exercise, and drinking alcohol may make these symptoms worse. Some foods may also trigger the symptoms of carcinoid syndrome, including foods high in:

  • Amines, such as aged cheeses, yeast extracts, tofu, sauerkraut, and smoked fish and meats

  • Serotonin, such as walnuts, pecans, plantains, bananas, and tomatoes

Carcinoid crisis

Carcinoid crisis is a term used when people experience severe, sudden symptoms of carcinoid syndrome, usually in times of extreme stress, such as surgery. Carcinoid crisis primarily includes serious fluctuations in blood pressure and heart rate. Carcinoid crisis is the most serious and life-threatening complication of carcinoid syndrome. It is generally recommended that patients receive intravenous octreotide (Sandostatin), a medication that helps control the production of hormones, before a planned surgery. Octreotide is also used to treat carcinoid crisis.

Managing symptoms

If a NET is diagnosed, relieving symptoms remains an important part of your care and treatment. This may be called palliative care or supportive care. It is often started soon after diagnosis and continued throughout treatment. Below is information on how some of the symptoms of a NET can be managed. Be sure to talk with your health care team about the symptoms you experience, including any new symptoms or a change in symptoms.

  • Facial flushing. Avoid stress. Ask your doctor about specific substances and foods, including alcohol, that can cause facial flushing so you can avoid them. Somatostatin analogs, like octreotide and lanreotide (Somatuline Depot), can help. Read more about somatostatin analogs in Types of Treatment.

  • Diarrhea. There can be many causes of diarrhea in people with a NET. If your diarrhea is caused by carcinoid syndrome, somatostatin analogs (octreotide and lanreotide) and telotristat ethyl (Xermelo) can help. In addition, there are other medications that can help control diarrhea, depending on what is causing it. Ask your doctor for specific recommendations.

  • Wheezing. Ask your doctor about the use of a bronchodilator, a medication that relaxes the muscles in the lungs to make breathing easier.

  • Heart valve problems. Tell your doctor immediately if you think you may have a problem with your heart. Signs of this problem include difficulty breathing and becoming easily tired during exercise.

Learn more about managing common cancer symptoms and treatment side effects.

The next section in this guide is Diagnosis. It explains what tests may be needed to learn more about the cause of the symptoms. Use the menu to choose a different section to read in this guide.