What are Neuroendocrine Tumors?

To understand what is a neuroendocrine tumor, it helps to learn about your neuroendocrine system, which encompasses your body’s nervous system and endocrine system.

Your nervous system includes the brain, spinal cord and the network of nerve cells that carry messages back and forth between the brain and spinal cord and other areas of the body. Your endocrine system includes various glands, such as the hypothalamus, pituitary, pineal, thyroid, parathyroid, pancreas, adrenal glands, ovaries, testicles and prostate. These glands produce the hormones that are necessary for digestion, reproduction, metabolism and controlling blood pressure and heart rate.

Neuroendocrine cells are specialized cells found throughout the body that function a little like nerve cells and a little like endocrine cells — they receive messages from the brain like nerve cells and release hormones in the body like endocrine cells.

A neuroendocrine tumor (NET) occurs when neuroendocrine cells begin to multiply and grow out of control, forming a tumor over time. Neuroendocrine tumors can occur anywhere in the body where neuroendocrine cells are found, but NETs are most commonly found in these areas:

  • Gastrointestinal tract, particularly the stomach, small intestine and rectum
  • Pancreas, accounting for 3 to 5% of pancreas tumors
  • Lungs, especially the bronchial tubes or airways

The location of the tumor can affect the hormones produced there and the processes they regulate. For example, a neuroendocrine tumor in the pancreas (which produces insulin) can affect metabolism and blood sugar.

While neuroendocrine tumors are considered a rare cancer type, incidence of NETs has been on the rise over the past 10 to 15 years. About 12,000 adults are diagnosed with NET in the United States each year.