Vipoma is a rare type of cancer that affects hormone-producing cells in the pancreas, known as islet cells.
The disease causes these cells to produce extremely high levels of vasoactive intestinal peptide (VIP), a hormone that regulates water transport in the intestines.
It is also called Verner-Morrison syndrome, after the two doctors who first described the disease in 1958.
Vipomas affect about one in 10 million people per year. Most of them occur as isolated tumors, but in some cases they are part of a bigger syndrome called multiple endocrine neoplasia type 1 (MEN 1).
Risk Factors
The exact cause of Vipoma is not known, although genetics are believed to be a factor. A family history of MEN and similar syndromes can also increase one’s risk. Most patients are adults in their 50s, and women are more likely to develop it than men.
Signs and Symptoms
The main symptom of Vipoma is extreme watery diarrhea, which lasts more than the usual run of two to three days. This eventually leads to dehydration and low potassium levels (hypokalemia). The diarrhea can occur intermittently for a year or more before the condition is diagnosed. Other symptoms include nausea, facial flushing, abdominal pain, reduced appetite, and unexplained weight loss.
Diagnosis and Staging
Vipomas are usually found incidentally while testing for other conditions, usually during a stool lest for prolonged diarrhea. Abnormal electrolyte levels can indicate cancer, but not necessarily VIPoma. Biopsies are usually avoided to reduce the risk for the patient. If Vipoma is suspected, the doctor will perform a blood test to check for high VIP levels, which confirms the diagnosis.
Computerized tomography (CT) scans and magnetic resonance imaging (MRI) can show the size and location of the tumor. Since some tumors have metastasized at the time of diagnosis, the doctor may also perform an octreotide scan, which tests for cancer in other parts of the body.
Prognosis
If the cancer is localized, VIPoma can be cured by surgically removing the tumor. However, about half of VIPoma cases have spread by the time they are diagnosed and are no longer curable. In such cases, the life expectancy is anywhere from a few days to a few months, depending on the degree of metastasis.
Treatment
The only curative option for VIPoma is surgery to remove the tumor, or in some cases, the entire pancreas (pancreatectomy). This presents a complete cure only if the tumor is confined to the pancreas. If the case is incurable, treatments are geared towatds relieving the symptoms and prevent further spread.
When palliative treatment is involved, the first goal is to prevent dehydration. Intravenous (IV) fluids are usually administered to replace the liquids lost in diarrhea. The next step is slowing the diarrhea itself. Octreotide, a synthetic version of the natural hormone somatostatin, blocks the action of VIP and reduces water loss.
Prevention
Because there is no known cause, the best line of prevention is regular screening and maintaining good overall health. Patients who have one or more risk factors, or who have previously been treated for endocrine tumors, should be tested at least once or twice a year.
