Islet cell tumors

Islet cell tumors, also called pancreatic neuroendocrine tumors (pNETs), are a diverse group of rare pancreatic lesions that make up about 5 percent of pancreatic tumors. The tumors grow slowly and develop within islet cells, the endocrine cells of the pancreas that produce hormones such as insulin, which regulates blood sugar.

Islet cell tumors are classified as functional or nonfunctional. If they produce excessive hormones that result in clinical symptoms, they are classified as functional. Otherwise, they are classified as non-functional.

The three most common functional islet cell tumors include gastrinoma, insulinoma and glucagonoma, all of which correspond to the different types of cells in which the tumor forms. The two types of rare functional islet cell tumors are called VIPomas and somatostatinomas. The methods for diagnosing these types of tumors can be different.

Northwell Health’s Pancreas Disease Center has extensive experience in the surgical treatment of islet cell tumors. Our skilled staff of surgeons, gastroenterologists, endocrinologists and nurse practitioners are dedicated to setting you on a path of health and wellness through innovative treatments and customized care.

We understand that diseases of the pancreas can be difficult to diagnose and treat. The wide range of symptoms and risk factors require careful testing and examination. We’ll guide you through the process, step-by-step—and once we make a thorough diagnosis, we’ll work with you to create a care plan with the best treatment options for you. 

Functional tumors generally over-produce different hormones, which in turn produce different symptoms. 

• Insulinoma form in the cells that make insulin. Symptoms generally include low blood sugar, dizziness, light headedness, weakness, confusion, tremors and visual changes. 
• Gastrinoma (Zoller-Ellision syndrome) form in the cells that make gastrin. Symptoms include abdominal pain, diarrhea and peptic ulcer disease. 
• Glucagonoma forms in the cells that make glucagon. Common symptoms of this tumor are skin rash (Necrolytic migratory necrolytic erythema), diabetes, diarrhea and deep vein thrombosis (DVT). 
• VIPomas (Verne-Morrison) are known to cause severe diarrhea (stools can be tea colored and odorless), dehydration, muscle weakness, hypokalemia (potassium deficiency in the bloodstream) and achlorhydria. 
• Somatostatinoma symptoms include weight loss, anemia, foul smelling and oily stools (steatorrhea), diabetes and gallbladder disease. These tumors represent the rarest of the pancreatic neuroendocrine tumor. 

Non-functional tumors do not initially produce signs or symptoms. (As a result, they are often quite advanced when they are discovered.)

Pancreatic neuroendocrine tumors are different from pancreatic adenocarcinomas, which are more common, making up 95 percent of all pancreatic tumors. Adenocarcinomas develop from the exocrine tissue of the pancreas; they have different risk factors and causes, distinct signs and symptoms and are treated in different ways with different prognoses.

Islet cell tumors have a better prognosis than adenocarcinomas, but they can be more difficult to detect and may have symptoms that don’t specifically point to islet cell tumors.

The primary known risk factor for developing an islet cell tumor is a rare genetic condition called Multiple Endocrine Neoplasia 1 (MEN 1), which causes an overproduction of parathyroid, pituitary gland, and pancreatic hormones.

Surgery

Surgery is the preferred method of treatment; the type of surgical procedure chosen is dependent on the tumor’s location and size.

• A Whipple procedure is performed for tumors located in the head of the pancreas. This surgery involves the removal of parts of the pancreas, small intestine, and gallbladder.
• A distal pancreatectomy is usually indicated if the tumor is found in the tail of the pancreas.
• Enucleation of pancreatic islet cell tumors can be performed on insulinomas and gastrinomas, which are typically less than 1 to 2 cms. The tumors are often on the surface of the pancreas so the tumor can be excised from the pancreas without removing pancreatic tissue.

Neuroendocrine tumors can be removed using minimally-invasive, laparoscopic or robotic surgery. Open surgery is normally performed if:

• The tumor is large (10 cms)
• There is presence of metastases
• There is invasion of the tumor into the major blood vessels around the pancreas

Medical therapy

Pancreatic neuroendocrine tumors grow slowly and generally do not respond well to conventional chemotherapy, which targets rapidly growing cells. However, the U.S. Food and Drug Administration (FDA) recently approved medication for the treatment of advanced pancreatic neuroendocrine tumors. Your physician can discuss these options with you.