Signs and symptoms of neuroendocrine tumours (NETs)

Symptoms will depend on where in the body the neuroendocrine tumour (NET) will depend on:

• where in the body the tumour is
• whether it overproduces hormones or not (functioning or non-functioning).

Non-functioning NETs do not overproduce hormones. They may cause symptoms such as pain if they grow into or press on nearby areas of the body. But they may not cause any symptoms and are sometimes only found during operations or tests for other conditions.

Functioning NETs overproduce hormones. When the hormones are released into the blood stream, this can cause symptoms. The type of hormone made depends on which gland the tumour is affecting. Different hormones can cause different symptoms.

The hormones released by some functioning NETs may cause a collection of symptoms that include diarrhoea and flushing. This is called carcinoid syndrome. This is more likely to happen with NETs in the small bowel that have spread to the liver.

Loss of appetite and weight loss may also be symptoms of a neuroendocrine tumour.

NETs in the digestive system

Symptoms of a NET in the digestive system may include:

• pain or discomfort in the tummy area (abdomen) that comes and goes
• feeling sick (nausea) or being sick (vomiting)
• diarrhoea
• heartburn and indigestion.

NETs in the lung

A NET in the lung may cause:

• recurrent chest infections
• shortness of breath
• wheezing
• a cough that doesn’t go away after 2 or 3 weeks
• a long-standing cough that gets worse
• coughing up blood
• pain when breathing or coughing.

Gastrinomas are rare functioning NETs that usually start in the pancreas or the upper part of the small bowel (duodenum). They sometimes make too much gastrin. Gastrin is a hormone that controls the amount of gastric acid that the stomach makes.

Too much gastrin causes the stomach to make more gastric acid. High levels of gastric acid can lead to sores (ulcers) in the stomach, the gullet (oesophagus) and the small bowel. There may be several ulcers. Often, these do not respond well to the usual medicines. This is often called Zollinger-Ellison syndrome.

Common symptoms of a gastrinoma include:

• feeling bloated or pain in the tummy area (abdomen)
• diarrhoea
• heartburn
• weight loss
• bleeding into the stomach
• feeling sick (nausea) or being sick (vomiting)
• tiredness caused by anaemia (a low level of red blood cells).

These rare functioning NETs are usually in the pancreas. They may make too much of a substance called vasoactive intestinal peptide (VIP).

Common symptoms of a VIPoma include:

• watery diarrhoea
• low levels of potassium because of the diarrhoea
• feeling weak and tired
• feeling sick (nausea) and being sick (vomiting).