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Pancreatic Neuroendocrine Tumors

Pancreatic neuroendocrine tumors (NETs) arise from neuroendocrine cells (also called islet cells) that are present in the pancreas organ and responsible for secretion of many chemicals and hormones responsible for control of that organ as well as other distant organs.

These pancreatic NETs or islet cell tumors are rare and occur in only about 2 of every 100,000 people. The pancreatic NETs account for less than 5% of all pancreatic cancers. The management of pancreatic NETs depends on the following:

  • Functional status. If the tumors over-produce a specific hormone that is causing symptoms related to the over production of that hormone, then it is a functionally active tumor. Majority of the pancreatic NETs are not functionally active.
    • Insulinoma
    • Gastrinoma
    • Glucagonoma
    • VIPoma
    • Non-functional NET
  • Tumor grade. The grade (1-3) of the pancreatic NET is determined by our colleagues in Pathology based on the differentiation status (that is, how mature are the tumor cells), expression of the Ki-67 protein and the number of actively dividing cells (mitotic rate).

Insulinoma

Insulinoma is a subtype of pancreatic NET's which produce the hormone insulin and is the most common subtype of functional neuroendocrine tumors.

As these tumors grow they produce large amounts of insulin which can cause low blood sugar. When the blood sugar gets too low patients can experience symptoms which include dizziness, confusion, abnormal behavior and even loss of consciousness.

Several endocrine tests are required to confirm the diagnosis of an insulinoma because there are several other reasons for low blood sugar. Once the diagnosis is confirmed with blood tests, imaging studies such as CT scan or PET-CT DOTATATE scan are used to localize the tumor. Surgical removal of the tumor is the preferred primary treatment, if possible, after imaging studies are completed.

Gastrinoma

A gastrinoma is a subtype of pancreatic NET which produces the hormone gastrin. The primary function of gastrin is to stimulate the stomach to produce acid to aid in the digestion of food.

As these tumor grow, they produce large amounts of gastrin which leads to very high levels of stomach acid. An increase in stomach acid can then lead to ulcer formation in the stomach and small intestine (also called Zollinger-Ellison Syndrome).

Patients may complain of acid reflux, abdominal pain and diarrhea which may improve with antacid medications. Blood tests to measure the level of gastrin can be falsely elevated if patients are taking antacid medications during the test and these may need to be discontinued prior to testing.

Surgical removal of the tumor is the preferred primary treatment, if possible, after imaging studies are completed.

Glucagonoma

A glucagonoma is a subtype of pancreatic NET which produces the hormone glucagon. The primary function of glucagon is to counter the effects of insulin. Normally when a person has not eaten for several hours, the blood sugar drops and glucagon is released. This causes breakdown of sugar stored in the form of glucagon which quickly brings the blood sugar back up to normal.

Glucagonomas continuously produce glucagon which can cause continuously elevated blood sugar and symptoms typically seen with diabetes. Other symptoms in patients with glucagonoma include rash, blood clots and depression. Surgical removal of the tumor is the preferred primary treatment, if possible, after imaging studies are completed.

VIPoma

A VIPoma is a subtype of pancreatic NET which produces the hormone vasoactive intestinal polypeptide (VIP). VIPomas will cause symptoms including profuse watery diarrhea, dehydration and electrolyte disturbances. These tumors are extremely rare.

Patients are treated with medication to decrease symptoms and often require intravenous fluid and electrolyte replacement. Surgical removal of the tumor is the preferred primary treatment, if possible, after imaging studies are completed.

Non-functional neuroendocrine tumors

Some tumors that arise from endocrine cells of the pancreas do not produce hormones and therefore do not produce any of the symptoms which are described above. These types of tumors are often detected incidentally on CT scan or other imaging studies obtained to work-up another medical problem.

Some of these tumors may grow quite large and cause upper abdominal discomfort as they compress surrounding structures. The challenge in the diagnosis of these types of tumors is to distinguish them from pancreatic adenocarcinoma which has a worse prognosis. Surgery is the primary treatment for non-functional neuroendocrine tumors after blood tests and imaging studies are complete.

Diagnosis

The diagnosis of pancreatic NET may require the following:

  • Anatomic scans (CT or MR scans)
  • Functional scans (PET-CT DOTATATE scan)
  • Blood (routine blood test and hormone levels)

Treatment of pancreatic neuroendocrine tumors

The management of pancreatic NET depends on the following:

  • Functional status
  • Tumor grade
  • Staging
  • Symptoms

Surgical removal of the tumor involving the pancreas may require partial resection of the pancreas if this has not spread. In patients where the tumor which has spread to the liver, surgical resection of part of the liver or other treatments to destroy these tumors may help to decrease the amount of hormone produced and thus improve symptoms.

In addition to surgery, there are several treatment options available for patients with GI-NETs, including somatostatin analogues, small molecule inhibitors, chemotherapy, targeted radiation / PRRT, liver directed therapy and clinical trials with novel drugs.

There is wide spectrum of pancreatic NETs and the prognosis for patients is much dependent on how early the tumor is treated. In very small, early tumors the cure rates are excellent, while in more advanced cases control of tumor and symptoms can be obtained with a combination of medical and surgical treatments.

At the Rogel Cancer Center, our experienced team of medical oncologists, surgeons, pathologists, endocrinologists, radiation oncologists, interventional radiologists come together to diagnose and treat these tumors.

Make an appointment or refer a patient

Patients are seen at the Rogel Cancer Center (maps and directions) and can get the process started by calling 734-647-8902. If you’re a health care provider, please call 800-962-3555.