VIPoma: watery diarrhoea, low potassium and treatment of a rare pancreatic tumour

Cancer Research UK explains that VIP stands for vasoactive intestinal peptide, a hormone that relaxes the muscles in the stomach and bowel and helps to control the balance of sugar, salt and water in the gut. VIPomas are rare neuroendocrine tumours (NETs) that start in the cells that make VIP. They are a type of functioning NET, meaning they make and release abnormal levels of a hormone, and they are also called gastroenteropancreatic NETs or pancreatic NETs.

Pancreatic Cancer UK says most pancreatic neuroendocrine cancers are non-functioning (60 to 90%), and that up to 40 in 100 are functioning, producing higher levels of certain hormones that cause specific symptoms. VIPomas are among the functioning types, alongside insulinomas, gastrinomas and glucagonomas, and are more commonly found in the tail of the pancreas.

Cancer Research UK says symptoms usually develop slowly, and that in most people the tumour has already started to spread to other parts of the body by the time it is diagnosed. The main symptom is loose or watery diarrhoea which can be severe, and other symptoms may include the following.

• Dehydration.

• A low level of potassium in the blood (hypokalaemia).

• Weight loss.

• Flushing of the skin of the face, neck and chest.

• Tummy pain, and bloating according to Pancreatic Cancer UK.

• Because of dehydration and low potassium: thirst, feeling weak and tired, headaches, feeling dizzy, weak muscles and muscle cramps.

Cancer Research UK says Verner Morrison syndrome is the name given to the collection of symptoms caused by high levels of VIP. It is also called VIPoma syndrome, pancreatic cholera, or WDHA syndrome, standing for watery diarrhoea, hypokalaemia and hypochlorhydria or achlorhydria (low stomach acid).

It is important to note, as the charity does, that these symptoms could be due to a VIPoma but can also be caused by more common medical conditions, so it is important to get them checked by a doctor rather than assume the cause.

You usually see your GP first. Cancer Research UK says they might organise some tests, and will decide if you need to see a specialist, often a gastroenterologist. Because VIPomas are rare tumours, your doctor might ask you to have tests that check for other conditions first. If cancer is suspected, further tests check the type of cancer, its size and whether it has spread. If tests show a VIPoma, you will be referred to a team with expertise in treating NETs.

The tests the charity lists include a blood VIP level (for which you must not eat beforehand), other blood tests to check your general health and levels of other substances raised by NETs, CT and MRI scans, radioactive scans such as octreotide scans and gallium PET scans, and an endoscopic ultrasound scan of the tummy to look at the stomach, pancreas and bile ducts and to take biopsies.

The pathologist grades the tumour. The charity says VIPomas are well differentiated, with 3 grades: grade 1 grows slowly, grade 2 at a moderate speed and grade 3 quickly. Stage describes size and spread, and pancreatic NETs have stages 1 to 4.

We do not know what causes most neuroendocrine cancers. Cancer Research UK lists inherited conditions such as multiple endocrine neoplasia 1 (MEN1) and Von Hippel-Lindau disease, and having a family history of cancer, as risk factors for pancreatic NETs, and says the treatment team will consider whether you have MEN1 because this might affect treatment decisions. Pancreatic Cancer UK similarly says a very small number of rare inherited genetic conditions are linked to pancreatic neuroendocrine cancer.

Cancer Research UK says the first treatment is to control symptoms and replace the fluids and minerals lost through diarrhoea, usually through a drip into the bloodstream. You may then have surgery to try to get rid of the cancer, but surgery is not always possible, for example if the tumour has already spread or you are not well enough. If surgery is not an option you continue to have treatment to help your symptoms.

Somatostatin analogues, which are man-made versions of a naturally occurring protein that slows hormone production, may be used to try to slow the tumour and help stop the diarrhoea. The most common drugs are octreotide and lanreotide. A dietitian may give advice if you have lost a lot of weight, and you may need vitamin or mineral supplements or tube feeding.

Surgery to remove the VIPoma is usually the main treatment. The charity describes major operations with risks, and that the type of operation depends on where the cancer is in the pancreas and its size. Examples include enucleation, which removes just the tumour, and distal pancreatectomy, which removes the narrow end and body of the pancreas. A multidisciplinary team (MDT) decides the best treatment, and a clinical nurse specialist is usually your main point of contact.

Care is delivered through NET specialist centres and teams, and a clinical nurse specialist can answer questions. Pancreatic Cancer UK points to Neuroendocrine Cancer UK as a source of more detailed information, a helpline with specialist nurses, peer support and a counselling team. For symptoms of dehydration or rapidly worsening weakness, contact your care team urgently, or use NHS 111 or A&E if you cannot reach them.