What are Neuroendocrine Tumors?

Neuroendocrine and carcinoid tumors are sometimes called “cancer in slow motion” because they start out small and grow slowly.

Carcinoid tumors are typically found in older adults, with the largest number of cases diagnosed with people in their 60s and 70s. These tumors are rare and only one or two cases in every 100,000 Americans will be diagnosed each year.

Neuroendocrine tumors have a much better prognosis than any other cancer tumor in the same organ. Patients with neuroendocrine tumors generally aren’t cured, but they can expect to live many years with the disease. 

Neuroendocrine tumors can occur anywhere in the body. They develop most commonly in the appendix, small intestine, rectum and lung. They occur less commonly in the stomach, pancreas, colon, ovaries, testis and cervix. Neuroendocrine tumors frequently move to the liver.

Neuroendocrine tumors can be classified as functional or nonfunctional.

  • Functional tumors secrete hormones that can cause symptoms including flushing, asthma attacks and diarrhea. Fewer than 10 percent of patients have functional tumors. 
  • Nonfunctional tumors don’t secrete hormones.

Symptoms of Neuroendocrine Tumors

Many people with neuroendocrine tumors experience no symptoms before they are diagnosed and may remain symptom-free for years. The mass of the neuroendocrine tumor pressing on an organ or hormones secreted by the tumor can cause symptoms. When there are symptoms caused by the presence of neuroendocrine tumors, the symptoms may be vague. They may include:

  • Gastrointestinal bleeding. Your doctor may find that you are anemic and that the cause of your anemia is bleeding inside your abdomen caused by a neuroendocrine tumor. 
  • Abdominal pain
  • Change in bowel habits. You may experience too few bowel movements, too many bowel movements or diarrhea.
  • Bloating
  • Appendicitis. If you have to have your appendix removed, your doctor may find a neuroendocrine tumor in the appendix.

Neuroendocrine tumors can secrete hormones that cause symptoms. This is called carcinoid syndrome. These symptoms include: 

  • Flushing or redness of the skin
  • Diarrhea
  • Carcinoid-related heart disease
  • Abdominal cramping or gastritis
  • Shortness of breath.
  • Wheezing
  • Skin rash and itching

Risk Factors

We don’t know a lot about what causes neuroendocrine tumors, so we don’t have many strategies to prevent them. We do know that people with certain risk factors are at a higher risk of developing neuroendocrine tumors.

These risk factors include:

If you have one of these risk factors, your doctor may watch you closely. If you are at extremely high risk, your doctor may choose to remove an organ, such as the thyroid, to prevent a neuroendocrine tumor from growing there.