Understanding neuroendocrine medical terms

Adjuvant treatment

Additional treatment in the form of chemotherapy or radiotherapy given after surgery to reduce the risk of the tumour coming back. Not generally used in the treatment of patients who have had surgery for a NET.


Taking a piece of tissue from the suspected tumour and having it analysed in the laboratory by a trained doctor called a pathologist.


Term first coined in 1906 to describe a tumour that grew much more slowly than usual cancers. “Carcinoid” was initially used to describe tumours that started in the tubular gut, but these are now more accurately described as a NET or gastroenteropancreatic (GEP) NET.

Carcinoid heart disease

If high levels of the hormone serotonin are produced over a long time, this can cause thickening of the heart valves and can lead to failure of the heart.

Carcinoid syndrome

A condition where some NETs produce increased levels of the hormone serotonin and cause a number of symptoms such as flushing (redness) of the face, diarrhoea (loose bowel motions), asthma or wheezing, heart failure, stomach cramps, swelling of the ankles, fast heart rate.

Chromogranin A (CgA)

CgA is a chemical/hormone found inside neuroendocrine cells. The level of this hormone can be raised in patients with a diagnosis of NET, or in patients taking proton pump inhibitors (tablets to reduce acid production in the stomach) and can be measured in the blood.

Clinical trial

A study that explores whether a treatment or device is safe and effective in humans, or to compare the results of patients taking a new treatment with the results of patients taking the standard treatment to determine if one treatment is better than the other.

Functioning tumour

NETs sometimes make too much of certain types of hormones, which cause symptoms when they are released into the blood stream. The type of hormone that is over-produced depends on the gland that is affected by the tumour.


Gastrin is a hormone that increases production of acid by the stomach.


Type of NET that usually starts in the pancreas or the upper part of the small bowel (duodenum), which may produce too much gastrin.


Glucagon is a hormone that increases the glucose (sugar) level in the blood.


Type of NET which occurs most often in the pancreas and usually produces too much glucagon.

Goblet cell carcinoid (GCC)

GCC starts in the appendix and has features of both a NET and a faster growing type of cancer called an adenocarcinoma when looked at under the microscope.


How the tumour cells look under the microscope. The grade gives an idea of how quickly the tumour may grow.

Grade 1 (low grade)

Cells look very much like normal cells and are usually slow-growing.

Grade 2 (moderate grade)

These tumours are somewhere in between low-grade and high-grade tumours in their appearance and behaviour.

Grade 3 (high grade)

Cells look very abnormal and are likely to grow more quickly.

Gut hormones

Hormones produced within the gut which can be measured in the blood – vasoactive intestinal peptide, gastrin, glucagon, somatostatin, pancreatic polypeptide.


Hormones are the body’s chemical messages that travel in the blood to other tissues or organs. They can affect many different processes such as growth, mood, sexual function, or how the body gets energy from the food that is eaten.

5-hydroxyindoleacetic acid (5-HIAA)

The hormone serotonin is broken down in the liver to 5-HIAA, and the levels of this can be raised in the blood or urine of patients with a diagnosis of NET.


Insulin is a hormone produced by the pancreas. Insulin controls the amount of sugar in the blood by moving it into the cells, where it can be used by the body for energy.


Tumours that can occur in any part of the pancreas. In patients with insulinomas, the tumour produces abnormally high levels of insulin, which causes low blood sugar levels (hypoglycaemia).


Ki-67 is a measure of the proliferation index (number of dividing/proliferating cells) of the tumour and can be determined from looking at the tumour under the microscope. The doctor that does this is called a pathologist.

Margin status

The edge or border of the tissue that was removed at the time of surgery.

Metaiodobenzylguanidine (MIBG) scan

A scan used to locate and diagnose certain types of tumours in the body such as a phaeochromocytoma.


Levels of metanephrines (breakdown products of the fight or flight hormone adrenaline or nor-adrenaline) can be measured in the blood and may be raised in conditions such as paraganglioma or phaeochromocytoma.

Multiple endocrine neoplasia (MEN) 1 or 2

This is a rare family syndrome and people who have this condition have a higher risk of developing NETs. This condition is associated with tumours of the endocrine (hormone-producing) glands in the body such as the pituitary gland in the brain, the parathyroid and thyroid glands in the neck, the adrenal glands (located on top of the kidneys) and the pancreas.

Neuroendocrine system

“Neuro” refers to nerve and endocrine to the network of glands and organs in the body that produce hormones. Neuroendocrine cells are found in the endocrine glands; adrenal glands, pancreas, thyroid, pituitary and in the ovaries and testes.

Neuroendocrine tumour (NET)

Tumour of the neuroendocrine system.


This is a rare family syndrome and people who have this condition have a higher risk of developing NETs. This disease particularly affects the skin and the nervous system.

N-terminal pro-brain natriuretic peptide (NT-ProBNP)

The level of NT-ProBNP in the blood can give us information about the functioning of the heart.

Octreotide scan

Neuroendocrine tumours often have somatostatin receptors (molecule or surface on a cell that somatostatin binds to). Radioactive octreotide, a drug similar to somatostatin, can bind to these receptors when injected into the bloodstream. A radiation-measuring device detects the radioactivity and composes scan pictures of this.

Pancreatic NET (pNET)

The location of the primary tumour (where the NET started) is the pancreas.

Pancreatic polypeptide (PP)

Pancreatic polypeptide is produced by the pancreas and helps control the release of other substances made by the pancreas. The amount of PP in the blood increases after a person eats.


Rare tumour that comes from the same tissue as a phaeochromocytoma and develops outside the adrenal glands with approximately 85% developing in the abdomen, 12% in the chest and 3% in the head and neck.


A rare type of NET arising in the adrenal glands (located above the kidneys).


Serotonin is a chemical in the blood and is popularly thought to be a contributor to feelings of well-being and happiness. Approximately 90% of serotonin is produced in the gut with the other 10% produced in the brain. It is broken down in the liver to 5-HIAA.

Somatostatin/Somatostatin analogue

Somatostatin is a hormone that regulates (control and slows down) several other hormones in the endocrine system. When a patient does not have enough natural somatostatin because of a hormone-producing tumour, a drug called a somatostatin analogue can be prescribed (examples would be octreotide or lanreotide).


Extremely rare NET that usually occurs in the pancreas or parts of the small bowel and may produce extra somatostatin.


A type of NET that usually occurs in the pancreas and can make too much of a substance called vasoactive intestinal peptide and cause symptoms including diarrhoea, decreased levels of a salt in the blood called potassium, feeling sick and being sick.

Von Hippel-Lindau (VHL) disease

This is a rare family syndrome and people who have this condition have a higher risk of developing NETs. Because of this disorder, patients may develop various different types of tumours, and not only in the neuroendocrine system. They can also develop kidney cancers and tumours of the adrenal glands called phaeochromocytoma.

Well-/poorly differentiated

Well-differentiated (Grade 1 and 2) NETs look more like normal cells under the microscope and spread more slowly than poorly or undifferentiated tumours (Grade 3).

Last updated: March 2023