The three main areas where NETs are found in the body are the gastrointestinal tract (digestive system), the pancreas, and the lungs.
*NETs found in the gastrointestinal system or the pancreas are called gastroenteropancreatic NETs (GEP-NETs).
Diagram showing where neuroendocrine tumors (NETs, which you may also hear referred to as carcinoid tumors, GI-NETs, GEP-NETs, pancreatic NETs and lung NETs) may develop in the body.
Gastrointestinal NETs (GI-NETs) are the most common type of NETs (previously called carcinoid tumors). They are found in the gastrointestinal (GI) tract, and include tumors that develop in the small intestine, appendix, stomach, colon, and the rectum.
NETs that occur in the GI tract or pancreas are sometimes grouped together and called gastroenteropancreatic neuroendocrine tumors, or GEP-NETs for short.
Pancreatic NETs (pNETs) may be classified as symptomatic or asymptomatic:
There are several subtypes of pancreatic NETs. Each is named according to the type of hormone or substance they produce, as shown in the table below.
|Pancreatic NET types||Main hormone or substance involved||Associated syndrome||Major symptoms|
|Gastrinomas||Gastrin||Zollinger-Ellison syndrome (ZES)||Ulcers|
|VIPomas||Vasoactive intestinal polypeptide (VIP)||Verner-Morrison syndrome||Watery diarrhea (pancreatic cholera), which can cause potassium deficiency in the blood or reduced acid secretion in the stomach|
|Glucose intolerance (diabetes)|
|Somatostatinoma||Somatostatin||n/a||High blood sugar (glucose)|
|Diarrhea (bulky, greasy)|
Lung NETs account for around one quarter of all NETs. Within this group there are two major types:
The most frequent symptoms of lung NETs are very common in other conditions, which can make lung NETs very difficult to diagnose.
These symptoms include:
Other rare NETs include those that start in the:
Sometimes, it is impossible to determine where the NET has originally started; in this case it is called carcinoma of unknown primary origin.
Find out how NETs are diagnosed and the tools doctors may use to help.Diagnosing
The emotional, physical, and social challenges of living with NETs.Living with NETs
Living with NETs is not something that you have to do alone. Find help and support.Get support