Definition

Neuroendocrine tumors (NETs) are a rare type of tumor that can make hormones. Hormones are usually made and released by the neuroendocrine system. This system is made up of special tissues and glands. The endocrine tissue is partially controlled by the brain. Hormones affect how the body works. Examples are the metabolic rate, blood flow, or breathing. They can also change the levels of materials in the blood, such as glucose or calcium.

NETs are found throughout the body in the cells of the:

• Gastrointestinal (GI) tract, lungs, or thymus gland
• Pancreas
• Skin
• Adrenal glands:
  • Pheochromocytoma
  • Adrenocortical carcinoma
• Nervous system— neuroblastoma
• Ovaries, cervix, or uterus—rare

In many cases, neuroendocrine tumors cannot be identified as a specific type of cancer. When this occurs, it is called neuroendocrine carcinoma.

Islet Cells in the Pancreas

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Causes

Cancer is when cells in the body split without control or order. These cells go on to form a growth or tumor. The term cancer refers to harmful growths. These growths attack nearby tissues. They also spread to other parts of the body. It's not clear exactly what causes these problems. It’s likely a mix of genes and the environment.

Risk Factors

The chances of NETs depend on the type of cancer. Your chances are higher if you:

• Eat a diet high in saturated fat—GI tract
• Smoke—lungs
• Spend excess amounts of time in the sun—skin
• Work with metals or toxins—lungs or skin

Symptoms

NETs may produce excess hormones. This can cause certain problems. In those that have them, they will differ based on where the tumor is and what hormones are affected.

General symptoms of cancer may include:

• Weight loss
• Fatigue
• Pain
• Chronic cough with or without blood
• Skin changes or sores that do not heal
• Bleeding—especially from the GI tract
• Digestive problems such as heartburn or problems swallowing
• Bladder or bowel changes

Diagnosis

The doctor will ask about your symptoms and health history. A physical exam will be done. In some cases, a tumor is found while looking for something else.

You may have:

• Blood and urine tests to look for hormone problems
• Biopsy —tissue is removed and checked under a microscope
• Imaging tests such as:
  • X-ray
  • CT scan
  • MRI scan
  • Ultrasound
  • Upper or lower GI series
  • Somatostatin receptor scintigraphy or 68Ga-DOTaTATE positron emission tomography

The physical exam and test results help find the cancer stage. Staging helps guide a treatment plan. NETs are staged from 0-4. Stage 1 is a very localized cancer. Stage 4 is a spread to other parts of the body.

Treatment

The treatment depends on the stage and type of cancer. In most cases, treatments are combined. Some can be used to ease symptoms caused by tumors or hormones that are causing problems.

Prevention

There is no way to prevent NETs since the cause is unknown.