What Is Glucagonoma?
Glucagonoma is a rare tumor involving the pancreas. Glucagon is a hormone produced by the pancreas that works with insulin to control the amount of sugar in your blood. Glucagonoma tumor cells produce large amounts of glucagon, and these high levels create severe, painful, and life-threatening symptoms. About 5 to 10 percent of neuroendocrine tumors that develop in the pancreas are glucagonomas.
What Are the Symptoms of Glucagonoma?
If you have a tumor that produces large quantities of glucagon, it will affect many aspects of your health. Glucagon balances the effects of insulin by regulating the amount of sugar in your blood. If you have too much glucagon, your cells don’t store sugar and instead sugar stays in your bloodstream.
Glucagonoma leads to diabetes-like symptoms and other painful and dangerous symptoms, including:
- high blood sugar
- excessive thirst and hunger due to high blood sugar
- frequently waking up at night to urinate
- a skin rash, or dermatitis, on the face, belly, buttocks, and feet that’s often crusty or filled with pus
- unintentional weight loss
- blood clots in the legs, which is also called deep vein thrombosis
What Are the Causes of Glucagonoma?
There are no known direct causes of glucagonoma. If you have a family history of a syndrome called multiple endocrine neoplasia type 1 (MEN1) you have a greater risk of developing glucagonoma. However, those who don’t have other risk factors can develop these tumors.
Glucagonomas are cancerous, or malignant, about 75 percent of the time. Malignant glucagonomas spread into other tissues, usually the liver, and start interfering with the function of other organs.
How Is Glucagonoma Diagnosed?
It can be difficult to diagnose glucagonoma. Often, the symptoms appear to be caused by another condition, and it may be years before the correct diagnosis is made.
Diagnosis is initially made with several blood tests. High glucagon levels are the hallmark of this condition. Other signs include high blood sugar, high levels of chromogranin A, which is a protein often found in carcinoid tumors, and anemia, which is a condition in which you have a low level of red blood cells.
Your doctor will follow up these tests with a CT scan of the abdomen to look for the presence of tumors.
Two-thirds of all glucagonomas are malignant. These tumors can spread throughout the body and invade other organs. Tumors are often large and can be 4 to 6 centimeters wide when they’re discovered. This cancer is often not discovered until it has spread to the liver.
What Treatments Are Available for Glucagonoma?
Treating glucagonoma involves removing tumor cells and treating the effects of an excess of glucagon on your body.
It’s best to begin treatment by stabilizing the effects of excess glucagon. This often involves taking a somatostatin analog drug, such as an injection of octreotide (Sandostatin). Octreotide helps to counteract the effects of glucagon on your skin and improve skin rash.
If you’ve lost a great deal of weight, you may need an IV to help restore your body weight. High blood sugar can be treated with insulin and close monitoring of your blood glucose levels.
You may also be given an anticoagulant medication, or blood thinner. This prevents the formation of blood clots in your legs, also known as deep vein thrombosis. For people at risk of deep vein thrombosis, a filter can be placed in one of your large veins, the inferior vena cava, to prevent clots from reaching your lungs.
Once you’re healthy enough, the tumor will likely be surgically removed. This type of tumor rarely responds well to chemotherapy. Surgery is most successful if the tumor is caught while it’s still confined to the pancreas.
Exploratory surgery of the abdomen may be done either laparoscopically, with small cuts to allow for cameras, lights, and tools, or by creating a larger open incision.
Most glucagonomas occur on the left side or tail of the pancreas. Removal of this section is called a distal pancreatectomy. In some people, the spleen is also removed. When the tumor tissue is examined under a microscope, it’s difficult to tell whether it’s cancerous. If it’s cancerous, your surgeon will remove as much of the tumor as possible to prevent it from spreading further. This may include part of the pancreas, local lymph nodes, and even part of the liver.
What Are the Complications of a Glucagonoma?
Excess glucagon leads to diabetes-like symptoms. High blood sugar can cause:
- nerve damage
- metabolic problems
- brain damage
Deep vein thrombosis can cause blood clots to travel to the lungs, and it can even cause death.
If the tumor invades the liver, it can eventually cause liver failure.
What Can I Expect in the Long Term?
Usually, by the time glucagonoma is diagnosed, the cancer has spread to other organs, such as the liver. Generally, surgery isn’t effective because it’s difficult to detect it early on.
Once a tumor is removed, the effect of excess glucagon decreases immediately. If the tumor is limited to only the pancreas, the five-year survival rate is 55 percent, meaning 55 percent of people live for five years after surgery. There’s a 15 percent five-year survival rate if the tumors aren’t able to be removed by surgery.