What are gastrinomas?

Gastrinomas are rare tumours that start in the neuroendocrine cells that make the hormone gastrin. There are neuroendocrine cells in most organs of our body, including the small bowel (duodenum) and pancreas. 

Gastrinomas make large amounts of the hormone gastrin. Gastrin controls the amount of acid in your stomach, which helps to digest food. Too much acid can cause ulcers in the stomach and the small bowel (duodenum). 

The combination of high levels of gastrin, too much acid and stomach or small bowel ulcers is called Zollinger Ellison Syndrome (ZES).

The pancreas and duodenum

The pancreas and duodenum are part of our digestive system.

The pancreas is a large gland that makes digestive juices and hormones. The juices flow down a tube (pancreatic duct) into the duodenum. The duodenum is the first part of the small bowel. 

Another duct called the bile duct joins the duodenum to the liver and the pancreas. The bile duct comes down from the gallbladder and liver and joins the duodenum right next to the pancreatic duct.

Where it starts

Around 70 out of every 100 gastrinomas (70%) start in the duodenum. Tumours that start in the duodenum are usually small (often less than 1 cm across). They are called duodenal gastrinomas.

About 25 out of every 100 gastrinomas (25%) start in the pancreas. Pancreatic gastrinomas usually start in the widest part of the pancreas (the head). The head of the pancreas is the part closest to the duodenum. Pancreatic gastrinomas are often bigger than duodenal gastrinomas. 

More rarely gastrinomas can start in the:

• stomach
• liver
• bile duct
• ovary
• heart
• lungs

How common it is

Gastrinomas are very rare. Only between 1 and 2 people in every million develop a gastrinoma every year.

Cancer or non cancer?

All gastrinomas are cancers. Some gastrinomas grow slowly and don't spread to other parts of the body. Others can spread to other parts of the body (metastases).

Gastrinomas that start in the pancreas are more likely to spread to other parts of the body, than gastrinomas that start in the duodenum:

• up to 35 out of every 100 pancreatic gastrinomas (35%) spread to the liver
• up to 10 out of every 100 duodenal gastrinomas (10%) spread to the liver

Gastrinomas can also spread to the nearby lymph nodes.