What Is Islet Cell Carcinoma?

Islet cell carcinoma, also referred to as an islet cell tumor, is a relatively uncommon disease that produces abnormal pancreatic tissue cells. The islet cell tumor is also sometimes called a pancreatic carcinoid, pancreatic endocrine tumor (PET), or islet cell carcinoma. These tumors fall into several distinct categories based on the types of endocrine pancreas cells that they affect. Whether there are symptoms and if the nature of those symptoms varies considerably depends on the tumors status as functional or non-functional. Diagnosis is usually made following laboratory and imaging tests.

Pancreatic endocrine cells produce hormones that control the functions of organs and cells throughout the body. These cells cluster together in the pancreas to form islets, also known as the islands of Langerhans. Islet cell tumors are referred to as functional tumors if their presence produces symptoms, or nonfunctional in cases where the tumor does not cause symptoms. Most functional tumors are benign, while most nonfunctional tumors are cancerous.

The specific types of islet cell carcinoma tumors are based on the hormones produced by the affected cells. A gastrinoma is a tumor that forms in pancreas cells that produce gastrin — a hormone that triggers release of stomach acid and thus aids in digestion. Found most commonly in the head of the pancreas, gastrinomas are usually malignant and often cause diarrhea. A glucagonoma tumor forms in cells that manufacture glucagen — a hormone that increases blood glucose levels — and these tumors often cause hyperglycemia. Most glucagonoma tumors are cancerous.

The insulinoma is a tumor that grows in insulin-producing cellular tissue which produces hormones that control the flow of glucose into the body's cells, providing energy. Insuloma tumors can develop in any part of the pancreas and are commonly benign. VIPomas tumors impact hormone production that controls the balance of water, sugar, and salt in the body, while somatostatinomas affect somatostatin-producing cells — a hormone that regulates cell proliferation and neurotransmission.

A nonfunctional islet cell carcinoma can take many years to develop and often causes no symptoms until and unless it reaches a size that causes mechanical difficulties in the body. General symptoms can include back or abdomen pain, indigestion, diarrhea, or a lump in the abdomen. Functional tumors produce symptoms based on the hormone production that is affected. These include recurring ulcers and digestive tract disease, as well as symptoms of low or high blood sugar. Unlike other forms of cancer, there are no standardized stages assigned to islet cell carcinoma; treatment is based on the number and location of the tumors and may consist of radiation or chemotherapy.