What is ViPoma?
Vasoactive intestinal peptide tumors (VIPoma) are a type of tumor that produces an excess of a hormone called vasoactive intestinal peptide (VIP). Werner and Morrison first identified these types of tumors in 1958, noting that they sometimes led to water-like diarrhea and a condition called hypokalemia (low potassium levels). In 1973, researchers Bloom, Polak, and Pearse confirmed that it was indeed the overproduction of VIP causing the symptoms.
These tumors can also bring about a condition known as Verner-Morrison syndrome, also known as WDHA syndrome or pancreatic cholera syndrome. It can cause watery diarrhea, hypokalemia, and hypochlorhydria or achlorhydria (conditions characterized by little to no stomach acid). The following information will explain how these tumors present themselves, how they’re diagnosed, and how they’re managed.
What Causes ViPoma?
VIP is a type of hormone made in your brain and in the nerve cells elsewhere in your body like your gut, lungs, and urinary system. It acts like a traffic conductor in your body, controlling a lot of important functions. It helps your blood vessels relax and widen, regulates the activity of smooth muscles – the muscles that control your gut movements, stimulates your gut to release water and salts, stops your stomach from producing too much acid and helps increase the blood flow, mostly in your gut.
Risk Factors and Frequency for ViPoma
VIPomas are rare tumors that can develop in both children and adults, occurring in about 0.05% to 2.0% of people. For adults, they usually appear between the ages of 30 and 50 and are mostly found in the pancreas (95% of cases). A smaller number have been associated with conditions like colorectal cancer, lung cancer, pheochromocytoma, neurofibroma, and ganglioneuroblastoma. While they usually occur on their own, about 5% of them are part of a condition known as multiple endocrine neoplasia type 1 (MEN1) syndrome. Sadly, by the time of diagnosis, more than half of these tumors have already spread to other parts of the body.
In children, VIPomas are usually diagnosed between the ages of 2 and 4. These tumors are often either ganglioneuromas or ganglioneuroblastomas, which originate from particular types of nerve tissue found in the chest cavity or the area behind the abdominal organs. Occasionally, these tumors may also develop from the adrenal gland.
Signs and Symptoms of ViPoma
VIPoma is a medical condition that is often signified by watery diarrhea. This continues even after refraining from eating for 48 hours. In many cases, people may have this type of diarrhea for several years before getting diagnosed. The stool is usually in large quantity, exceeding 700 ml per day even during fasts, and could reach over 3000 ml per day in about 70% of the patients. This type of stool is odorless, tea-colored, and can cause noteworthy loss of body fluids and important minerals like potassium.
Additional symptoms make include feeling tired, experiencing nausea, vomiting, muscle weakness, and muscle cramps. These symptoms arise due to dehydration and a reduction in potassium level – a condition known as hypokalemia. Skin flushing has been noticed in about 8% to 20% of patients. Muscle spasms, known as tetany, have been reported which occur due to low magnesium levels – a condition known as hypomagnesemia. If the loss of body fluids and minerals gets severe, it can lead to irregular heartbeats, muscle disease, spasms, and a type of shock caused by low blood volume, referred to as hypovolemic shock.
In children suffering from VIPoma, symptoms can also include failure to thrive, along with chronic diarrhea.
Testing for ViPoma
If your doctor suspects you might have VIPoma, which is a rare type of tumor that typically occurs in the pancreas, they will need to perform several tests. VIPoma is usually diagnosed in patients who have a specific type of watery diarrhea and a raised level of a hormone called VIP (Vasoactive Intestinal Peptide) in their blood. Normally, the level of VIP is less than 190 pg/ml in the blood, but in patients with VIPoma, it will usually be somewhere between 250 to 500 pg/ml.
However, as the release of VIP can occur intermittently, it is important to repeat these blood tests to make sure they are accurately diagnosing the disease. This is particularly necessary when the patient is experiencing symptoms, to make sure the results aren’t mistakenly coming back as normal.
In children suspected of having VIPoma, another hormone called catecholamine will also need to be measured. Pancreatic polypeptide levels, a protein created by the pancreas, may be elevated in tumors originating from the pancreas.
VIPoma can also cause imbalances in other elements of your blood, like a decrease in your potassium, chloride, and magnesium levels. It could increase your blood sugar and calcium levels as well. The alterations in potassium and chloride can lead to a specific type of acid build-up in your body caused by loss of these elements in your digestive system. The increase in calcium could be due to dehydration, a simultaneous presence of a disease called MEN1 syndrome, or the tumor secreting a specific substance that affects calcium. Low magnesium levels could be a result of severe diarrhea. The increase in blood sugar is due to an effect of VIP on your liver that prompts it to release more sugar.
On the imaging side, your doctor would typically begin with a specific type of CT scan known as a helical multiphasic contrast-enhanced CT scan, which can detect over 80% of these tumors in the pancreas. If they see some unclear results or if they need to confirm if the tumor has spread, they might order an MRI, especially to detect any spread to the liver.
Somatostatin receptor scintigraphy is another test your doctor might consider. This test uses a radioactive substance that can help identify tumors that could be hiding other parts of the body by attaching a traceable element to a hormone that the tumor cells take in.
Endoscopic ultrasound is another diagnostic tool that helps your doctor view the pancreas in detail and determine how much the disease has progressed. They might also take a small sample of the tumor with a needle during this procedure for further tests. Finally, in certain cases, your doctor might use a highly specific imaging technique that involves a radioactive diagnostic agent, called 68-Ga DOTATATE, which has been approved by the FDA for detecting somatostatin receptor-positive neuroendocrine tumors in adults and children. This helps them to accurately diagnose and plan the treatment.
Treatment Options for ViPoma
When treating VIPoma, which is a rare type of cancer, doctors typically begin with a combination of medication and surgery. Initially, the focus of treatment is on controlling the symptoms and quickly and effectively replenishing lost fluids and electrolytes that the body needs to function properly.
One type of medication doctors use for this purpose is somatostatin analogs, such as octreotide and lanreotide. These drugs help to reduce the secretion of a hormone called VIP which is responsible for causing the symptoms of VIPoma.
Other types of medications, such as glucocorticoids and interferon-alpha, may be used in patients who don’t respond well to somatostatin analogs. These are typically used as another attempt to control the symptoms.
As for surgery, the ultimate goal is to remove the tumor completely or as much as possible. If the complete removal of the tumor is not possible, then a procedure known as surgical debulking may be performed. This surgery involves removing a portion of the tumor, which can provide some relief from the symptoms.
Unfortunately, in as many as 60% of cases, the VIPoma is found to have spread, or metastasized, by the time it is detected. Most commonly, the cancer spreads to the liver, lymph nodes, bones, and kidneys. In case of liver metastases, surgical resection of the liver is performed when feasible. Otherwise, procedures like radiofrequency ablation and cryoablation may be used to treat small metastases. Hepatic artery embolization is another treatment option for patients with unresectable liver metastases. This is a palliative treatment that can help to alleviate symptoms but is not intended as a cure.
Systemic chemotherapy is another treatment option used for patients with large tumors or extrahepatic metastases. However, the overall response to systemic chemotherapy isn’t particularly promising.
Newer types of drugs, such as sunitinib and everolimus, have been approved in the United States for treating advanced, well-differentiated pancreatic neuroendocrine tumors, including VIPomas. These drugs have an action that inhibits certain enzymes (proteins that speed up chemical reactions in the body), in turn helping to control the growth of cancer cells.
What else can ViPoma be?
In adults living in developed countries, there are several potential causes for a type of condition called “secretory diarrhea.” These include:
- Overuse of laxatives
- Carcinoid syndrome (a type of cancer that can affect the digestive tract)
- Microscopic colitis (a type of swelling or inflammation in the intestines)
- Bile salt malabsorption, which can happen after a surgery to remove part of the small intestine
Before making a final diagnosis, doctors also have to check for infections such as Vibrio cholera or Escherichia coli, which are more common causes of diarrhea in developing countries.
They need to keep an eye on two things. One, “secretory diarrhea” can sometimes occur with certain gut disorders like Crohn disease and short bowel syndrome. Two, Munchausen syndrome by proxy could be a rare reason. This is when caregivers deliberately make someone else (usually a child) sick.
In children, genetic defects that affect the way body salts are transported can also cause “secretory diarrhea.” Two examples are “congenital chloride diarrhea” and “congenital sodium diarrhea.” These usually show up in early infancy.
What to expect with ViPoma
The average life expectancy of patients suffering from VIPoma, a rare type of tumor often found in the pancreas, is about 96 months. Survival rates can depend on several factors such as the severity and stage of the tumor, and if it is operable by surgery or not.
Recent guidelines by the National Comprehensive Cancer Network (NCCN), a non-profit alliance of leading cancer centers, recommend a specific plan to monitor the recovery of patients after tumor removal surgery. This includes a complete health assessment, detailed scans like CT or MRI, and blood tests to check for ‘VIP’ levels in the body, over the first 3 to 12 months. After the first year, these checks are recommended every 6 to 12 months to ensure optimal recovery and prevent any recurrence of the tumor.