Glossary and definitions

Carcinoid syndrome

Carcinoid syndrome is a set of symptoms that may occur in patients who have carcinoid tumors (neuroendocrine tumors, or NET, often in the gastrointestinal tract or lungs) and is caused by the increased production of hormones. Not all people with carcinoid tumors have carcinoid syndrome1

Chromogranin A (CgA) Test

Serum CgA is a blood test used for the monitoring of a carcinoid tumor2

Computed tomography (CT) Scan

A scan that uses X-rays to take a series of detailed cross-sectional images through the body1


A “dry” redness, usually of the chest and face sometimes encompassing the whole body, and not usually associated with sweating1


Where neuroendocrine cancer cells produce and release abnormal amounts of the hormone or chemical they are usually responsible for3

Gastroenteropancreatic neuroendocrine tumor (GEP-NET)

A Neuroendocrine Tumor of the GastroEnteroPancreatic system – in other words a NET that may occur in the stomach, duodenum, small bowel or pancreas3


The scientific term for a type of sugar that is gained from food and can be found in the blood1

Glycemic index (GI)

A figure representing the relative ability of a carbohydrate food to affect the level of glucose (sugar) in the blood1


Substances that are secreted by cells to communicate with cells in the same or different parts of the body to help the body function normally1

5-hydroxyindoleacetic acid (5-HIAA)

A by-product of serotonin, a substance normally secreted in the body, but produced in excess when a patient has functional carcinoid tumors; 5-HIAA is useful in the diagnosis of functional carcinoid tumors4

Immune system

The complex group of defense responses found in humans that helps fight disease-causing organisms (pathogens)1


Is a protein present in cells and is involved in cell growth and division. By using this protein to stain cancer cells, an assessment can be made as to how slowly or quickly the cancer cells are likely to grow and spread. The higher the percentage the quicker growth can occur5

Liver burden

The liver is the predominant site of metastatic disease in patients with NETs, the term describes how much tumor burden is within the liver6

Magnetic resonance imaging (MRI)

A method of obtaining cross-sectional images of a patient, using a magnetic fields and radio waves instead of X-rays1


A new tumor produced by the transfer of cancer cells from the site of the original tumor1

Neuroendocrine tumor (NET)

Tumor(s) arising in neuroendocrine cells throughout the body, most commonly occurring in the gastrointestinal tract, lungs, or pancreas7


Where neuroendocrine cancer cells usually retain their ability to release normal amounts of hormone or chemicals3

Positron emission tomography (PET)

Scans used to produce detailed images of the inside of the body. PET scans are often combined with CT scans to produce even more detailed images, known as a PET/CT scan1

Primary site

Is a term used to describe where, in the body, the cancer started1

Peptide receptor radionuclide therapy (PRRT)

Another term for radioligand therapy (RLT)8

Radioligand therapy (RLT)

A therapy using a radioligand (a protein, usually similar to the hormone somatostatin, that is combined with a small amount of radioactive material) that damages tumor cells by a targeted dose of radiation from inside the tumor cells8

Secondary site

Is a term used to describe cancer has that has spread beyond the primary site. May also be describe as metastasis (for one secondary cancer) or metastases (to described more than one secondary cancer) 1


A hormone commonly involved in carcinoid syndrome and contributes to other conditions like carcinoid heart disease and fibrosis1


The naturally occurring hormone produced in many parts of the body that signals the pituitary gland to reduce the production of growth hormone2

Somatostatin analog (SSA)

Treatment that reduces the amount of hormones produced by the tumor, helping to control symptoms and slow tumor growth. Often administered as first-line therapy7

Somatostatin receptor (SSTR)

Cell surface proteins that bind somatostatin and trigger intracellular changes which influence the behavior of cells. Often expressed on GEP-NET tumor cells and are a target for treatment3

Symptom control

Means the relief of distressing physical, emotional, and social symptoms the patient is experiencing. It does not mean "cure of disease"1


A collection of rapidly dividing cancer cells which are capable of detaching and travelling to other parts of the body to make more tumors1

Tumor differentiation

A term that describes how a tumor looks under a microscope compared to the normal tissue around it. If a NET is well differentiated, it may grow and spread very slowly. If a NET is poorly differentiated, it often grows and spreads rapidly5

Tumor grade/grading

Is an essential assessment and measurement of how neuroendocrine cancer cells are developing. How slowly or quickly they are growing or likely to grow5

Tumor staging

Tells us whether the cancer is localized (limited to the area in which it arises) or disseminated (has spread to other places in the body). Staging is usually assessed by scans9


The taking in or absorption of a substance by a living organism or bodily organ

References: 1. NET Patient Foundation. The NPF Handbook. Available at: Accessed: October 2021. 2. Sansone A, Lauretta R, Vottari S, et al. Specific and Non-Specific Biomarkers in Neuroendocrine Gastroenteropancreatic Tumors. Cancers (Basel). 2019; 11(8): 1113. 3. Diez M, Teulé A, and Salazar R. Gastroenteropancreatic neuroendocrine tumors: diagnosis and treatment. Ann Gastroenterol. 2013; 26: 29-36. 4. Niederle B, Pape U-F, Costa F, et al. ENETS consensus guidelines update for neuroendocrine neoplasms of the jejunum and ileum. Neuroendocrinology. 2016; 103(2): 125–138. 5. Cancer.Net. Neuroendocrine Tumors: Grades. Available at: Accessed: October 2021. 6. Strosberg J, Kunz PL, Hendifar A, et al. Impact of liver tumour burden, alkaline phosphatase elevation, and target lesion size on treatment outcomes with 177Lu-Dotatate: an analysis of the NETTER-1 study. Eur J Nucl Med Mol Imaging. 2020; 47(10): 2372-2382. 7. Oronsky B, Ma PC, Morgensztern D, et al. Nothing But NET: A Review of Neuroendocrine Tumours and Carcinomas. Neoplasia. 2017; 19(12): 991-1002. 8. Cancer Research UK. Peptide receptor radionuclide therapy (PRRT). Available at: Accessed: October 2021. 9. Cancer.Net. Neuroendocrine Tumor of the Gastrointestinal Tract: Stages and Grades. Available at: Accessed: October 2021.