Pancreatic Neuroendocrine Tumors

Pancreatic neuroendocrine tumors (islet cell tumors) are tumors that start in your pancreas’ endocrine cells. These rare tumors cause symptoms that may feel like common medical issues. Early diagnosis and treatment make a difference, with more than 90% of people with this condition being alive five years after diagnosis.


What is a pancreatic neuroendocrine tumor?

Pancreatic neuroendocrine tumors (also called islet cell tumors or pancreatic NETs) are rare tumors that start in your pancreas’ endocrine cells. Your pancreas is a flat pear-shaped gland tucked beside your stomach and small bowel. Endocrine cells in your pancreas make hormones that manage digestion and blood sugar levels. A pancreatic NET may affect your digestive system or your blood sugar levels.

Pancreatic neuroendocrine tumors can be cancerous or noncancerous.

How common are pancreatic neuroendocrine tumors?

They’re rare. The most recent data estimates that 5 in 1 million people develop a type of pancreatic neuroendocrine tumor.

Types of pancreatic neuroendocrine tumors

Healthcare providers classify pancreatic neuroendocrine tumors as being functioning or nonfunctioning:

  • Functioning pancreatic NETs may release excessive amounts of hormones, the chemicals that carry messages throughout your body that tell it what to do and when to do it.
  • Nonfunctioning pancreatic NETs don’t release hormones, but they can cause issues if they grow large enough to press on nearby organs, like your belly.

There are several types of pancreatic NETs, each with different characteristics. Some but not all of them are cancerous, meaning they can spread from your pancreas to other parts of your body. Some cause other conditions or have links to other conditions. All the tumors below are functioning pancreatic NETs.

Pancreatic neuroendocrine tumor types are:

  • Insulinomas. This is the most common type of functional pancreatic NET, accounting for about 70% of all pancreatic neuroendocrine tumors. Most insulinomas are benign (noncancerous.) Insulinomas affect the cells that release insulin, the hormone that keeps your blood sugar from getting too high.
  • Gastrinomas. About 50% of gastrinomas are cancerous. This tumor affects the cells that release gastrin, which triggers your stomach to produce gastric acid. Too much gastric acid in your stomach causes ulcers, acid reflux and other issues.
  • Glucagonomas. Glucagonomas are slow-growing tumors that usually are cancerous. They affect the cells that release glucagon, the hormone that keeps your blood sugar from getting too low.
  • VIPomas. VIP stands for “vasoactive intestinal peptide,” a hormone that relaxes the muscles in your stomach and bowels and manages the balance of sugar, salt and water in your digestive tract.
  • Somatostatinomas. These are slow-growing cancerous tumors. They affect the cells that release somatostatin. About 10% of people with somatostatinomas develop somatostatinoma syndrome, which increases their risk of diabetes and/or gallstones.


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Symptoms and Causes

What are the symptoms of pancreatic neuroendocrine tumors?

Symptoms vary depending on the type of pancreatic NET, but common symptoms include:

What causes pancreatic neuroendocrine tumors?

Researchers don’t know the exact cause. Approximately 10% of pancreatic neuroendocrine tumors are linked to inherited conditions or syndromes.


What are the complications of this condition?

The most significant complication is that the tumors can spread to your lungs, liver or bones. But they may also increase your risk of developing other medical conditions:

  • Insulinomas are associated with conditions including multiple endocrine neoplasia type 1 (MEN1), von-Hippel Lindau disease and neurofibromatosis type 1 (NF1). They can cause low blood sugar that can be difficult to manage.
  • Gastrinomas may cause ulcers, acid reflux and the digestive disorder Zollinger-Ellison syndrome.
  • Glucagonomas are associated with MEN1. They can cause high blood sugar that can be difficult to manage.
  • VIPomas are often cancerous, but even noncancerous VIPomas may cause other medical issues like severe diarrhea.
  • Somatostatinomas may cause somatostatinoma syndrome, which increases the risk of diabetes and/or gallstones.

Diagnosis and Tests

How are pancreatic neuroendocrine tumors diagnosed?

Healthcare providers do physical examinations, including asking about specific symptoms, how long you’ve had symptoms and if your symptoms are getting worse. They’ll ask about your medical history, including if anyone in your biological family has certain inherited disorders that have an association with pancreatic neuroendocrine tumors.

What tests are done to diagnose pancreatic neuroendocrine tumors?

Healthcare providers do several tests, including:

Often the only way to confirm a diagnosis of pancreatic NET is to do a biopsy or a laparotomy.

What are pancreatic NET stages and grades?

Healthcare providers use test results to establish pancreatic neuroendocrine tumor stages, grades and whether the tumors are functioning or nonfunctioning:

  • Stages describe cancerous tumor size and if it’s spread to your lymph nodes or other parts of your body.
  • Grades describe how quickly cancerous cells may multiply.
  • Functioning versus nonfunctioning, or whether tumors release hormones.

Healthcare providers use the TNM cancer staging system to classify pancreatic NETs. (In TNM staging, T stands for tumor size and location, N stands for whether tumors affect nearby lymph nodes and M stands for whether tumors have metastasized.) The stages of pancreatic neuroendocrine tumors are:

  • Stage I: The tumor measures less than 2 centimeters across and hasn’t spread from your pancreas.
  • Stage II: It measures more than 4 centimeters across and/or has spread into your duodenum (the first part of your small intestine) or to your bile ducts.
  • Stage III: The tumor has spread to nearby lymph nodes or nearby organs or large blood vessels.
  • Stage IV: The tumor is in more distant organs and tissues, such as your liver or bones.

Pancreatic NET grades describe how quickly a cancerous tumor may grow and spread. Healthcare providers set tumor grades based on what a medical pathologist learns about the tumor’s cells. The tumor grades are:

  • Well-differentiated grade 1: Tumor cells aren’t multiplying very fast, and the cells look more like normal cells than abnormal cells.
  • Well-differentiated grade 2: Tumor cells have characteristics that fall in between those of low- and high-grade tumors.
  • Well-differentiated grade 3: Tumor cells are multiplying more quickly, and cells look more abnormal.
  • Poorly differentiated NET: Tumor cells are multiplying very quickly and cells look extremely abnormal. These are the most aggressive and are also called high-grade neuroendocrine carcinoma (NEC) or small cell cancer.


Management and Treatment

What are treatments for pancreatic neuroendocrine tumors?

The most common treatment is a pancreatectomy to remove a tumor. Specific surgeries vary depending on tumor location in your pancreas. Your healthcare provider may use terms like “head” and “tail” when they talk about specific surgery. That’s because your pancreas is shaped like a fish, with a wide head, a medium-sized middle or body and a narrow tail. Common pancreatectomies are:

  • Whipple procedure: This is the most common surgical treatment for pancreatic neuroendocrine tumors. In this procedure, surgeons remove the part of your pancreas, along with the tumor and several nearby organs.
  • Central pancreatomy: Surgeons remove the central body part of your pancreas, leaving the pancreas’ head and tail.
  • Distal pancreatomy: They remove the pancreas tail. They may remove part of the pancreas body and some or all of your spleen. (Your spleen and pancreatic tail are closely connected.)

Healthcare providers may do other types of surgery and the following treatments:

What are common treatment side effects?

There are many ways to treat pancreatic NETs and just as many side effects. Side effects will vary depending on the treatment type:

  • Surgery: Pain, infection and bleeding.
  • Chemotherapy: Fatigue, nausea and vomiting, hair loss and diarrhea.
  • Hormone therapy: Soreness at the site where the medication was injected.
  • Liver transplant: Blood clots, hemorrhage, bile duct injury and liver failure.
  • Peptide receptor radionuclide therapy: Kidney damage and nausea.
  • Tyrosine kinase inhibitor: Fatigue, fever, weight loss or weight gain.

As you go through treatment, consider talking to your healthcare team about palliative care. Palliative care offers support services and care for people with serious illnesses, including ways to manage treatment side effects.

Outlook / Prognosis

What are pancreatic neuroendocrine tumor survival rates?

Survival rates vary depending on the pancreatic NET type, its grade and whether the tumor was in other parts of your body at the time of diagnosis. The National Cancer Institute (U.S.) tracks the rate of people with cancer who were alive five years after diagnosis. The five-year survival rates for pancreatic NETs are:

  • More than 50% overall.
  • More than 90% in cases where the tumor hasn’t spread.
  • More than 70% in cases where the tumor is in nearby tissues or lymph nodes.
  • More than 20% when the tumor is in more distant areas of your body, like your liver or lungs.

If you’re wondering about survival rates, it’s important to remember that this is information based on other people’s experiences with a pancreatic NET. It’s also information based on what’s happened in the past. You’re unique, and so is your potential survival rate. Talk to your healthcare team about survival rate data. They know you and your situation, which means they’re your best resource.

What’s the life expectancy for someone with a pancreatic neuroendocrine tumor?

That’s hard to say. In general, people who receive treatment before a pancreatic NET has spread may have nearly normal life expectancies, particularly if they’re alive more than five years after diagnosis. Just like survival rates, your healthcare team is your best resource for information about your life expectancy.

Living With

How do I take care of myself?

Just as there’s no single type of pancreatic neuroendocrine tumor, there’s no single or best way to take care of yourself. In general, you should:

  • Get as much rest as you can. Fatigue is a common symptom of the condition and a side effect of treatment.
  • Try to eat a healthy, well-balanced diet. If pancreatic NET symptoms and treatment side effects make eating difficult, ask a nutritionist for suggestions on finding foods you can tolerate and that will help you keep up your strength.
  • Consider mental health support. If you’re having a hard time emotionally, ask your provider about services that might help you manage your feelings so you can focus on your health.

Pancreatic neuroendocrine tumors are rare. You may feel like no one else can understand what you’re experiencing. If that’s your situation, ask your provider if there are support groups you can join.

When should I see my healthcare provider?

You should see your healthcare provider if you notice changes in your body, like your original symptoms worsening. These changes might be unrelated to your condition, and the best way to be sure is to talk to your provider.

What questions should I ask my healthcare provider?

Pancreatic neuroendocrine tumors are rare, and you may not know much about them. Here are some questions you may want to ask your healthcare provider:

  • What type of pancreatic neuroendocrine tumor do I have?
  • Could a medical pathologist with experience with neuroendocrine tumors review tissue samples from my biopsy?
  • Will I need surgery?
  • What are surgery side effects and complications?
  • What are the other treatments for this condition?

Additional Common Questions

What’s the difference between a pancreatic neuroendocrine tumor and an adenocarcinoma?

Adenocarcinomas are cancers that start in your glandular epithelial cells. These cells are in glands lining your organs, including your pancreas.

Pancreatic neuroendocrine tumors are only in endocrine cells in your pancreas. In general, pancreatic neuroendocrine tumors are slower growing and have a much better prognosis compared to pancreatic adenocarcinoma.

A note from Cleveland Clinic

All serious medical conditions are challenging. But the challenges may feel like they’re doubled or even tripled when the condition in question is a rare one like a pancreatic neuroendocrine tumor (pancreatic NET). You may find yourself hunting for information about these tumors, which affect specific cells in your pancreas. And you may feel overwhelmed as you try to process what you’re learning and anxious about what happens next.

Your healthcare providers understand that having a rare disease like a pancreatic NET may be an upsetting experience. If you have a pancreatic NET and have questions, don’t hesitate to ask your team for information about what you can expect.

Medically Reviewed

Last reviewed on 10/10/2023.

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