What are stomach neuroendocrine tumours?

Stomach neuroendocrine tumours (NETs) are rare stomach tumours that start in the neuroendocrine cells of the stomach.

They often develop slowly and don’t always have specific symptoms. So, they might be found during investigations or tests for other problems. You might hear some types of stomach NET being called carcinoid tumours.

What are neuroendocrine cells?

Neuroendocrine cells are part of our neuroendocrine system. Neuroendocrine cells don’t form an actual organ. Instead, they are scattered throughout other organs like the oesophagus, stomach, pancreas, intestines and lungs. They make hormones which control how our bodies work.

The digestive system is large and has more neuroendocrine cells than any other part of the body.

In the stomach, neuroendocrine cells help control the release of digestive juices and how fast food moves through the stomach. They may also help control the growth of other types of digestive system cells.

The stomach

The stomach is part of the digestive system. It's in the upper left side of the tummy (abdomen). The top of the stomach joins the bottom of the food pipe (oesophagus) and the other end is joined to the bowel. 

It is a muscular bag that has three main parts. They are the:

• top (fundus)
• middle (body) 
• bottom (antrum or pylorus) 

At each end of the stomach there is a valve called a sphincter. These valves control the movement of food through the digestive system.

They are the:

• cardiac sphincter - at the top joining the oesophagus to the stomach
• pyloric sphincter - which is at the bottom joining the stomach to the bowel

How the stomach works

Food passes from the oesophagus into the stomach. The stomach then stores the food and breaks it down (digests it) so our body can absorb it. It does this by producing gastric juice which mixes with the food, so it is easy to digest.

Glands in the inner lining of the stomach make gastric juice. It contains stomach acid, water and a protein called pepsin. It begins to flow as soon as we smell something. The stomach muscle contracts, churning the food with the juice, which changes it to a thick liquid. It takes a couple of hours for this to happen. Then the liquid moves into the bowel where the body absorbs it.

The stomach continues to produce gastric juice and hormones, even when it’s empty. It also produces a thick mucus to protect the lining of the stomach from the acid and pepsin.
 

How common are stomach NETs?

Stomach NETs are rare stomach tumours. Around 1 out of every 100 stomach tumours (around 1%) are a stomach NET.

Most NETs start somewhere in the digestive system (gut). Around 5 out of every 100 neuroendocrine tumours (around 5%) start in the stomach.

They are slightly more common in women. They are more common in people over the age of 60 than younger people.

Risks and causes

A risk factor is anything that increases your risk of getting a disease. Different diseases have different risk factors.

Stomach NETs can be associated with chronic atrophic gastritis. This is a long lasting inflammation of the stomach.

Your risk of developing a neuroendocrine tumour is higher if you have an inherited endocrine cancer syndrome called multiple endocrine neoplasia 1 (MEN1).

MEN 1 is a rare inherited condition in which 2 or more tumours develop in the pancreas, parathyroid gland and pituitary gland. Tumours can also develop in the bowel, stomach and adrenal glands. The tumours can be non cancerous (benign) or cancer (malignant).

Having a family history of cancer is a risk factor for all types of NET including stomach NETs.

What next?

You might be interested to read about the possible symptoms of stomach NETs.