Overview
Islet cell tumors are abnormal cells that form in the tissues of the pancreas.
The pancreas is a gland about 6 inches long that is shaped like a thin pear lying on its side. The wider end of the pancreas is called the head, the middle section is called the body, and the narrow end is called the tail. The pancreas lies behind the stomach and in front of the spine.
There are two kinds of cells in the pancreas:
• Endocrine pancreas cells make several kinds of hormones (chemicals that control the actions of certain cells or organs in the body), such as insulin to control blood sugar. They cluster together in many small groups (islets) throughout the pancreas. Endocrine pancreas cells are also called islet cells or islets of Langerhans. Malignant islet cell tumors are a rare type of pancreatic cancer.
• Exocrine pancreas cells make enzymes that are released into the small intestine to help the body digest food. Most of the pancreas is made of ducts with small sacs at the end of the ducts, which are lined with exocrine cells.
An islet cell tumor may also be called a pancreatic endocrine tumor (PET), pancreatic neuroendocrine tumor, islet cell carcinoma, or pancreatic carcinoid.
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Source: National Cancer Institute
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Tumor Types
Islet cells make different kinds of hormones such as gastrin, insulin, and glucagon. Types of functional islet cell tumors include the following:
• Gastrinoma: A tumor that forms in cells that make gastrin. Gastrin is a hormone that causes the stomach to release an acid that helps digest food. Both gastrin and stomach acid are increased by gastrinomas. When increased stomach acid, stomach ulcers, and diarrhea are caused by a tumor that makes gastrin, it is called Zollinger-Ellison syndrome. A gastrinoma usually forms in the head of the pancreas and sometimes forms in the small intestine. Most gastrinomas are malignant (cancer).
• Insulinoma: A tumor that forms in cells that make insulin. Insulin is a hormone that controls the amount of glucose (sugar) in the blood. It moves glucose into the cells, where it can be used by the body for energy. Insulinomas are usually slow-growing tumors that rarely spread. An insulinoma forms in the head, body, or tail of the pancreas. Insulinomas are usually benign (not cancer).
• Glucagonoma: A tumor that forms in cells that make glucagon. Glucagon is a hormone that increases the amount of glucose in the blood. It causes the liver to break down glycogen. Too much glucagon causes hyperglycemia (high blood sugar). Glucagonomas are often malignant. A glucagonoma usually forms in the tail of the pancreas. Most glucagonomas are malignant (cancer).
• Other types of tumors: There are other rare types of functional islet cell tumors that make hormones, including hormones that control the balance of sugar, salt, and water in the body. These tumors include:
• VIPomas, which make vasoactive intestinal peptide. VIPoma may also be called Verner-Morrison syndrome.
• Somatostatinomas, which make somatostatin.
These other types of tumors are grouped together because they are treated in much the same way.
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Source: National Cancer Institute
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Symptoms
Symptoms can be caused by the growth of the tumor and/or by hormones the tumor makes. Some tumors may not cause symptoms. Conditions other than islet cell tumors can cause the symptoms listed below. Consult a doctor if any of these problems occur.
Signs and symptoms of a non-functioning islet cell tumor
A non-functioning islet cell tumor may grow for a long time without causing symptoms. It may grow large or spread to other parts of the body before it causes symptoms, such as:
• Diarrhea.
• Indigestion.
• A lump in the abdomen.
• Pain in the abdomen or back.
• Yellowing of the skin and whites of the eyes.
A tumor that makes pancreatic peptides (PPoma) often has no symptoms.
Signs and symptoms of a functioning islet cell tumor
The symptoms of a functioning islet tumor depend on the type of hormone being made.
Too much gastrin may cause:
• Stomach ulcers that keep coming back.
• Pain in the abdomen, which may spread to the back. The pain may come and go and it may go away after taking an antacid.
• The flow of stomach contents back into the esophagus (gastroesophageal reflux).
• Diarrhea.
Too much insulin may cause:
• Low blood sugar. This can cause blurred vision, headache, and feeling lightheaded, tired, weak, shaky, nervous, irritable, sweaty, confused, or hungry.
• Feeling a fast heartbeat.
Too much glucagon may cause:
• Skin rash on the face, stomach, or legs.
• High blood sugar. This can cause headaches, frequent urination, dry skin and mouth, or feeling hungry, thirsty, tired, or weak.
• Blood clots in the lung. This can cause shortness of breath, cough or pain in the chest. Blood clots in the arm or leg can cause pain, swelling, warmth, or redness of the arm or leg.
• Diarrhea.
• Weight loss for no known reason.
• Sore tongue or sores at the corners of the mouth.
Too much vasoactive intestinal peptide (VIP) may cause:
• Very large amounts of watery diarrhea.
• Dehydration. This can cause feeling thirsty, making less urine, dry skin and mouth, feeling tired, headache, or dizziness.
• Low potassium level in the blood. This can cause muscle weakness, aching, or cramps, numbness and tingling, frequent urination, and feeling a fast heartbeat, confused, or thirsty.
• Cramps or pain in the abdomen.
• Weight loss for no known reason.
Too much somatostatin may cause:
• High blood sugar. This can cause headaches, frequent urination, dry skin and mouth, or feeling hungry, thirsty, tired, or weak.
• Diarrhea.
• Steatorrhea (very foul-smelling stool that floats).
• Gallstones.
• Yellowing of the skin and whites of the eyes.
• Weight loss for no known reason.
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Source: National Cancer Institute
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Treatment
Different types of treatments are available for patients with islet cell tumors. Some treatments are standard (the currently used treatment, often referred to as “standard of care”), and some are being tested in clinical trials. A treatment clinical trial is a research study meant to improve current treatments or obtain information on new treatments for patients with cancer. When clinical trials show that a new treatment is better than the standard treatment, the new treatment may become the standard treatment. Patients may want to think about taking part in a clinical trial. Some clinical trials are open only to patients who have not started treatment.
Five types of standard treatment are used:
Surgery
An operation may be done to remove the tumor. One of the following types of surgery may be used:
• Enucleation: Surgery to remove the tumor only. This may be done when cancer occurs in one place in the pancreas.
• Whipple procedure: A surgical procedure in which the head of the pancreas, the gallbladder, nearby lymph nodes and part of the stomach, small intestine, and bile duct may be removed. Enough of the pancreas is left to make digestive juices and insulin. The organs removed during this procedure depend on the patient's condition.
• Distal pancreatectomy: Surgery to remove the body and tail of the pancreas. The spleen may also be removed.
• Total gastrectomy: Surgery to remove the whole stomach.
• Parietal cell vagotomy: Surgery to cut the nerve that causes stomach cells to make acid.
• Liver resection: Surgery to remove part or all of the liver.
• Radiofrequency ablation: The use of a special probe with tiny electrodes that kill cancer cells. Sometimes the probe is inserted directly through the skin and only local anesthesia is needed. In other cases, the probe is inserted through an incision in the abdomen. This is done in the hospital with general anesthesia.
• Cryosurgical ablation: A procedure in which tissue is frozen to destroy abnormal cells. This is usually done with a special instrument that contains liquid nitrogen or liquid carbon dioxide. The instrument may be used during surgery or laparoscopy or inserted through the skin. This procedure is also called cryoablation.
Chemotherapy
Chemotherapy is a cancer treatment that uses drugs to stop the growth of cancer cells, either by killing the cells or by stopping them from dividing. When chemotherapy is taken by mouth or injected into a vein or muscle, the drugs enter the bloodstream and can reach cancer cells throughout the body (systemic chemotherapy). When chemotherapy is placed directly into the spinal column, an organ, or a body cavity such as the abdomen, the drugs mainly affect cancer cells in those areas (regional chemotherapy). Combination chemotherapy is the use of more than one anticancer drug. The way the chemotherapy is given depends on the type of the cancer being treated.
Hormone therapy
Hormone therapy is a cancer treatment that removes hormones or blocks their action and stops cancer cells from growing. Hormones are substances made by glands in the body and circulated in the bloodstream. Some hormones can cause certain cancers to grow. If tests show that the cancer cells have places where hormones can attach (receptors), drugs, surgery, or radiation therapy are used to reduce the production of hormones or block them from working.
Hepatic arterial occlusion or chemoembolization
Hepatic arterial occlusion uses drugs, small particles, or other agents to block or reduce the flow of blood to the liver through the hepatic artery (the major blood vessel that carries blood to the liver). This is done to kill cancer cells growing in the liver. The tumor is prevented from getting the oxygen and nutrients it needs to grow. The liver continues to receive blood from the hepatic portal vein, which carries blood from the stomach and intestine.
Chemotherapy delivered during hepatic arterial occlusion is called chemoembolization. The anticancer drug is injected into the hepatic artery through a catheter (thin tube). The drug is mixed with the substance that blocks the artery and cuts off blood flow to the tumor. Most of the anticancer drug is trapped near the tumor and only a small amount of the drug reaches other parts of the body.
The blockage may be temporary or permanent, depending on the substance used to block the artery.
Supportive care
Supportive care is given to lessen the problems caused by the disease or its treatment. Supportive care for islet cell cancer may include treatment for the following:
• Stomach ulcers may be treated with drug therapy, such as:
• Proton-pump inhibitor drugs such as omeprazole, lansoprazole, or pantoprazole.
• Histamine blocking drugs such as cimetidine, ranitidine, or famotidine.
• Somatostatin-type drugs such as octreotide.
• Diarrhea may be treated with:
• Intravenous (IV) fluids with electrolytes such as potassium or chloride.
• Somatostatin-type drugs such as octreotide.
• Low blood sugar may be treated by having small, frequent meals or with drug therapy to maintain a normal blood sugar level.
• High blood sugar may be treated with drugs taken by mouth or insulin by injection.
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Source: National Cancer Institute
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