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Somatostatinoma

This page is about somatostatinoma, a very rare type of tumour that develops in the pancreas or small bowel. There is information about

 

What somatostatinoma are

Somatostatinomas are rare tumours that can develop in the pancreas or small bowel. Pancreatic tumours most commonly develop in the head of the pancreas.

position_of_pancreas2

small_bowel

Somatostatinomas develop in hormone producing cells called islet cells. There are different types of islet cells, each producing different hormones. Delta islet cells make the hormone somatostatin.

Somatostatin cuts off production of other hormones by the pancreas and controls how the gut works. Somatostatinomas produce extra somatostatin, which eventually leads to symptoms.

Somatostatinomas are extremely rare. Most are cancerous (malignant) and the rest are benign (non cancerous) tumours. It may not always be possible to tell if you have a benign or a malignant tumour. The tests you have such as an MRI scan or CT scan may show if the tumour has spread to the nearby lymph nodes or elsewhere. But it may not be until you have surgery that you know for certain if it is benign or malignant.

Somatostatinomas are usually slow growing and symptoms tend to develop slowly. People with cancerous tumours often have a secondary cancer at diagnosis.

Somatostatinomas are a type of neuroendocrine tumour. Neuro means nerve and endocrine means hormone producing. Neuroendocrine tumours (NETs) are tumours that develop in cells that are triggered by nerve cells to produce hormones.

Somatostatinomas are a particular type of gastroenteropancreatic neuroendocrine tumour (GEP NET). They are also called pancreatic neuroendocrine tumours (pNETs or PETs). 

There is a separate page about neuroendocrine tumours.

 

Risks and causes of somatostatinomas

We don’t know what causes most somatostatinomas.

People who have a rare family cancer syndrome called Multiple Endocrine Neoplasia Type 1 (MEN 1) or neurofibromatosis have a higher risk of somatostatinoma.

 

Symptoms of somatostatinoma

The symptoms are caused by an increase in the amount of the hormone somatostatinoma. They may start slowly and become worse. They include

  • Gallstones
  • Weight loss
  • Diarrhoea
  • Fatty stools
  • Yellowing of the skin and whites of the eyes called jaundice, which is more common if the tumour develops in the small bowel
  • Abdominal pain
  • Blockage in the bowel
  • Diabetes mellitus

Symptoms of diabetes mellitus include feeling thirsty, a dry mouth, passing urine frequently, weight loss, tiredness, and blurred vision.

 

Tests to diagnose somatostatinoma

The first tests you have are blood tests to check your general health. You will also have a blood test to check the amount of somatostatin in your blood. With this test you don’t eat anything for 8 hours beforehand.

Other tests include

Endoscopic ultrasound is an ultrasound scan done from inside your body. You have an endoscopy but the endoscope contains a small ultrasound probe. The ultrasound helps the doctor to find areas that might be cancer and guide a small needle into them. They then remove a sample of cells (a biopsy).

An octreoscan is called somatostatin receptor scintigraphy (SSRS). You have an injection of a substance called octreotide and then have a scan using a special type of scanner. Octreotide is taken up by some neuroendocrine tumour cells. Doctors can attach a radioactive substance to the octreotide that shows up on the scan.

You may also have tests to check for MEN-1. This includes blood tests to check your levels of parathyroid hormone, calcium, and the hormone prolactin.

 

Treating somatostatinoma

The main treatment for somatostatinoma is surgery. But surgery is not always possible. Some cancerous somatostatinomas have already spread when they are diagnosed. If you can’t have surgery to try and cure somatostatinoma, you will have treatment to control your symptoms.

Surgery

Surgery that removes the whole tumour aims to cure somatostatinoma. The type of surgery you have depends on

  • Whether you have one or more tumours
  • Where the tumour is
  • The size of the tumour

You may have surgery to remove

  • Just the tumour
  • The whole of your pancreas – a total pancreatectomy
  • The head of the pancreas – a pylorus preserving pancreaticoduodenectomy (PPPD)
  • The head of the pancreas and part of your stomach – a Whipples operation
  • The tail of your pancreas – distal pancreatectomy

Whichever operation you have, if your tumour is cancerous you will have the nearby lymph nodes removed as well.

If the somatostatinoma has spread to your liver you may be able to have the liver tumour removed at the same time. This may be just the tumour, or part of the liver too.

These are major operations and there are risks with having this type of surgery. But this type of surgery is to try to cure your somatostatinoma so you may feel it is worth some risks

You can read more about surgery for tumours in the pancreas and possible side effects on the page about surgery to try to cure pancreatic cancer.

Treating symptoms of somatostatinoma

Some cancerous (malignant) somatostatinomas are diagnosed when they are already advanced. And some tumours come back after treatment. The most common place for malignant somatostatinoma to spread to is the liver.

Not everyone with non cancerous (benign) somatostatinoma can have surgery. This may be due to other medical conditions or the position of the tumour. If the whole tumour cannot be removed, you will have treatment to control the amount of somatostatin produced by the tumour.

The aim of treatment for somatostatinomas that can’t be completely removed is to control any symptoms you have rather than cure them. Treatments may include

If your cancer has spread and is causing symptoms you may have surgery to remove some of the tumour. Removing part of the tumour can reduce your symptoms. This includes removing tumours in your liver. Your doctor will only suggest surgery if it is possible to remove at least 90% of the tumour.

As it is major surgery and there are risks, you need to think carefully about the benefits. Will it improve your quality of life enough to make it worth having such a big operation? Your surgeon will talk to you about the risks and benefits and answer any questions you have.

Instead of having a major open surgery you may be able to have radiofrequency ablation, cryotherapy, or transarterial chemoembolisation (TACE) to reduce your symptoms. Or you mave selective internal radiotherapy (SIRT).

Radiofrequency ablation uses heat made by radio waves to kill cancer cells. Cryotherapy uses a cold probe to destroy cells and tissue by freezing.

TACE is when your doctor injects chemotherapy directly into the area of the tumour in the liver. You also have an injection of another substance which blocks the blood supply to the tumour. This substance may be a gel or tiny plastic beads and helps to keep the chemotherapy around the tumour.

SIRT is when microscopic beads that are coated with a radioactive substance called Yttrium-90 are injected into the blood supply to the liver. This is a type of targeted radiotherapy.

Chemotherapy can help to control symptoms of a somatostatinoma that can’t be removed with surgery. The drugs you may have include doxorubicin, streptozocin and fluorouracil.

You may have a somatostatin analogue drug such as octreotide or lanreotide to help control diarrhoea and diabetes. There is information about somatostatin analogues in the carcinoid section of this website. Carcinoids are another type of neuroendocrine tumour and are treated with somatostatin analogues.

If you have diabetes you will have treatment to control your blood sugar. This is usually tablets, but some people may need to have insulin.

Interferon is a type of biological therapy. It can help to control symptoms for some people with malignant neuroendocrine tumours. You have interferon as an injection under the skin.

 

Research into somatostatinoma

Research is always more difficult with rare conditions. There are fewer people available to take part in trials, so it takes longer to recruit enough people.

There is research looking into diagnosing and monitoring these tumours. There is also research into treatment with different types of chemotherapy and biological therapies.

New biological treatments include drugs like sunitinib (Sutent), everolimus (Afinitor) and bevacizumab (Avastin). These types of treatment work on tumours that have particular proteins.

A recent phase 3 trial found that people having everolimus for advanced neuroendocrine tumours (NETs) had a longer time before their cancer started growing again compared to people having a dummy drug (placebo). The average time before the tumour started growing again was 11 months compared to 4.6 months in people having the placebo.

Another phase 3 trial comparing sunitinib with a placebo for advanced NET found that the average time before the cancer started growing again was 11.4 months, compared to 5.5 months in people having the placebo.

The All Wales Medicines Strategy Group (AWMSG) and the Scottish Medicines Consortium say that sunitinib and everolimus should be available on the NHS. You should be able to have sunitinib or everolimus if other treatments are not working and you have pancreatic neuroendocrine tumours that cannot be removed with surgery, or have spread to other parts of the body. In England NICE have not looked at these drugs for NET. They may be available through individual funding through your PCT or through the cancer drugs fund if your doctor thinks they may be helpful.

Researchers are also looking into targeted radiotherapy (radio labelled treatment). You may also hear this called peptide receptor radioligand therapy (PRRT). This is a way of getting radiotherapy directly to individual tumour cells.

Cells have receptors that particular proteins can attach to. PPRT works in a similar way to an octreoscan. By attaching radiotherapy to a substance that attaches to the cancer cell receptors, you can deliver radiotherapy to them. It is too early in the research to know how well this treatment will work for somatostatinomas.

We need more research to find out which of these new treatments work best and when to use them.

To find out more about neuroendocrine trials go to our clinical trials database.

 

Coping with somatostatinoma

Coping with a rare condition can be difficult both practically and emotionally. Being well informed about your condition and possible treatments can make it easier to make decisions and cope with what happens.

It can also help to talk to people with the same condition. But it can be hard to find someone with a rare tumour. Check out Cancer Chat – Cancer Research UK’s discussion forum. It is a place to share experiences, stories and information with other people who know what you are going through.

You might also find it our general coping with cancer section helpful.

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Updated: 20 March 2014