Neuroendocrine Tumors (NETs)

A doctor chats with a patient who is about to get a gamma scan.

Neuroendocrine tumors (NETs) are a rare but complex type of cancer that can arise in many parts of the body. Because NETs are uncommon, it’s important to get care from doctors with expertise in this condition.

The OHSU Knight Cancer Institute is one of the few hospitals in the nation with a team focused on NETs. We offer:

  • A multidisciplinary approach, in which experts from different specialties work together. You benefit from their combined knowledge.
  • The latest diagnostic techniques.
  • The latest therapies, including radiopharmaceuticals like PRRT.
  • A wide range of clinical trials for promising new therapies.
  • A full range of support services for you and your family.

Understanding NETs

Despite their name, NETs don’t usually occur in the brain.  They start in the neuroendocrine cells. These cells are found in many organs throughout your body. They listen to signals from nerve cells and respond by making hormones that they release into the bloodstream.

Sometimes these cells begin to divide and grow out of control, forming tumors. Sometimes these tumors disrupt your hormone levels and throw your body out of balance.

Most NETs grow slowly and don’t spread. But some grow faster and can spread to other parts of the body.

About 95% of NETs develop in the digestive tract, the pancreas or in the lungs. They can be difficult to diagnose because they may cause no or few symptoms.

We use the term NETs to describe a vast range of tumors, but each NET is as unique as each patient. This means we tailor your treatment to your specific tumor.

Functioning and nonfunctioning NETs

Most NETs are nonfunctioning, which means they do not produce hormones.

But some NETs are functioning, which means they can disrupt your hormone levels. These NETs cause hypersecretion, or over-production of hormones. Here are some examples:

  • Gastrinomas: These tumors make gastrin, which causes the stomach to make acid to digest food. Too much gastrin can lead to stomach ulcers (open sores) and pain.
  • Insulinomas: These make insulin. Too much can lead to low blood sugar, which can cause confusion, fatigue, irritability, weakness and lightheadedness.
  • Glucagonomas: These make glucagon, which raises blood sugar levels. Too much can cause diabetes, with symptoms such as thirst and frequent urination. Patients can also develop other symptoms, including a red blistering rash on the face, stomach or legs.
  • Somatostatinomas: These tumors make somatostatin, which controls other hormones. Symptoms of too much somatostatin include high blood sugar, diarrhea, gallstones, jaundice, weight loss and foul-smelling stools.
  • VIPomas: These produce vasoactive intestinal peptide. Too much can cause symptoms such as severe watery diarrhea, thirst, headaches, dizziness, fatigue, weight loss, muscle weakness and belly pain or cramps.
  • PPomas: These make pancreatic polypeptide, which helps regulate the pancreas. Symptoms can include watery diarrhea, belly pain and an enlarged liver. 

NETs are rare. Roughly five in 100,000 people in the U.S. are diagnosed with a NET each year. But incidence rates are rising, in part because tests are getting better.

Researchers are still trying to figure out the cause of NETs. A small portion of NETs are linked to inherited genetic conditions such as:

  • Multiple endocrine neoplasia Type 1, or MEN1
  • Neurofibromatosis Type 1
  • Von-Hippel Lindau syndrome

We offer genetic counseling if you think you might have a family history of cancer.

  • Gastroenteropancreatic NETs (also called GEP-NETs): These are the most common NETs. They include both small intestine NETs and pancreatic NETs.
  • Pancreatic NETs (PNETs): These arise in the pancreas, the gland that controls digestion and blood sugar levels. PNETs may disrupt the hormone system that governs digestion, thirst and hunger. They are sometimes known as islet cell tumors because they form in cell clusters that resemble islands. 
  • Small intestine NETs (also known by the older term carcinoid tumor): These slow-growing tumors are found in the lining of the gastrointestinal tract, which has more neuroendocrine cells than anywhere in the body. About 8,000 cases of this type are diagnosed in the U.S. every year.
  • Bronchopulmonary NETs: These are tumors that develop in the lungs and airways.
  • Neuroendocrine carcinomas (NECs): These are rare but often aggressive cancers that require prompt treatment.
  • Merkel cell carcinoma: This uncommon skin cancer typically grows in areas with high sun exposure. Symptoms include firm bumps that are usually red, pink or purple. About 1,500 cases are diagnosed in the U.S. every year. More than 9 in 10 people affected are older than 50, and more than 9 in 10 cases are found in white people.
  • Medullary thyroid carcinoma: This cancer develops in the cells that produce calcitonin, which controls the amount of calcium in the body.
  • Pheochromocytomas and paragangliomas: These extremely rare tumors form in the adrenal glands or along the spinal cord. They release hormones that cause high blood pressure, elevated heart rate and other issues.
  • Rare NETs: NETs can also arise in the kidneys, the thymus and the thyroid.

Survival rates for NETs

A key concept in understanding survival is five-year relative survival rate. This is the percentage of people who are still alive five years after they were first diagnosed, compared to the general population. (It doesn’t count death from other causes.)

Survival rates for NETs are hard to predict because the condition can take so many forms and develop in so many parts of the body.

The five-year relative survival rate for gastrointestinal NETs is 94%, according to the American Cancer Society. This rises to 97% if the NET is caught in the earliest stage.

The five-year relative survival rate for pancreatic NETs is 53%. This rises to 95% if the PNET is caught in the earliest stage.

It's important to remember that these figures are averages and can't predict the outcome for any one patient. It's also important to remember that these figures are based on the treatments that were available more than five years ago. Patients who are diagnosed now may have a better outlook. Treatments are getting better all the time.

Patients can live with a NET for many years, which makes it vital to get expert treatment.

Signs and symptoms of NETs

NETs are often misdiagnosed at first. Some patients have no symptoms, while others have symptoms that mimic conditions like irritable bowel syndrome. Some NETs produce a surge of hormones, causing symptoms such as:

  • Flushing
  • Diarrhea
  • Asthma-like wheezing
  • Abdominal pain
  • Fatigue
  • Skin changes
  • Nausea
  • Weight loss
  • Unusual bleeding

Your care team may use the following tests to detect a NET:

  • Blood/urine test: Your doctor may order blood or urine tests to check hormone levels. Higher-than-normal levels may indicate a NET, although further testing is likely. You may need to fast before this test.  
  • Biopsy: A doctor called a pathologist looks at a tissue sample under a microscope. How normal or abnormal cells look can indicate how fast the NET may grow.
  • Endoscopy: A doctor inserts a flexible scope with a camera into the digestive tract through the throat or rectum. You will be sedated. The doctor can take samples of any tissue that looks abnormal.
  • Endoscopic ultrasound: Similar to endoscopy but includes an ultrasound probe to provide images. The gastroenterology doctors who perform this procedure at OHSU are experts, doing hundreds of endoscopic ultrasounds a year.  
  • Wireless capsule endoscopy: You swallow a capsule that looks like a big vitamin pill but is actually a camera. It takes pictures of your insides over about eight hours and sends them to a recorder worn on your waist.  
  • MRI scan: Magnetic resonance imaging scans take pictures of your insides. They offer excellent detail of your soft tissues, such as your liver and pancreas. MRI scans are not invasive. You lie on a scanner and hold still. The scanner uses a large magnet, radio waves and sophisticated computers. MRI scans take longer than CT scans, and they tend to be noisy. Learn more about MRI scans.
  • CT scan: Computed tomography or CAT scans take pictures of your insides. They offer excellent details of bones, organs and blood vessels. They are often used to see how far NETs have spread. CT scans are not invasive. You lie on a scanner and hold still. The scanner uses X-rays and sophisticated computers. Learn more about CT scans.
  • PET scan: Positron emission tomography scans take pictures of your insides at the molecular level. They are good at pinpointing cancer cells anywhere in your body. A small amount of radioactive substance called a tracer is injected into the bloodstream. The tracer homes in on cancer cells, and emits radiation detected by a special camera. PET scans are not invasive. You lie on a scanner and hold still.
  • PET/CT: This scanner does PET and CT at the same time.
  • PET/MRI: This scanner does PET and MRI at the same time. It is particularly good at detecting NETs. We are the first hospital in the Pacific Northwest to offer this advanced technology. Learn more about PET/MRI scans.
A nuclear medicine technician holds a tube in a laboratory.
Radiopharmaceuticals are drugs that contain radioactive particles. The drugs attack tumors from the inside. This is a promising new therapy for NETs.

Treatment for NETs

The Knight Cancer Institute has a multidisciplinary team of experts who focus on NETs.

  • Your team will include experts in surgery, medication, radiation, imaging, and more.
  • Each patient, and each NET, is unique. Your team will talk with you and with one another to recommend a treatment plan.
  • We can also test tumors for genetic mutations to guide treatment.
  • We treat patients with every stage of disease. If a cure is out of reach, treatment can give you the longest survival and best quality of life possible.


Surgically removing NETs is usually the best first option. We use minimally invasive laparoscopic surgery (also known as keyhole surgery) when we can.

If the entire tumor can't be removed, we take out as much as possible to ease symptoms and improve your quality of life.

Somatostatin analog therapy

Somatostatin analogs are medications given by shot that slow a tumor's hormone production and control its growth. OHSU was one of the first centers to use this therapy, leading to Food and Drug Administration approval.

Targeted therapy

Targeted therapy works at the molecular level, attacking cancer cells while minimizing damage to healthy cells. Targeted therapies for NETs include:

  • Everolimus (Afinitor), a pill that can lengthen survival for patients with some NETs of the pancreas, gastrointestinal tract or lung. It may be combined with somatostatin analog therapy.
  • Sunitinib malate (Sutent), a capsule used to treat some NETs of the pancreas. It lengthens survival by stopping cancer cells from dividing and by preventing tumors from developing blood vessels.

Radiation therapy

Radiation therapy uses targeted beams of energy to kill cancer cells. For NETs, it's often used to control cancer that has spread to another part of the body.

Nuclear medicine

Nuclear medicine is a newer type of treatment for NETs that combines the precision of targeted therapy with the power of radiation therapy. It uses radioactive drugs called radiopharmaceuticals.

The Knight Cancer Institute was one of the first hospitals to offer this therapy for NETs. Our research helped earn FDA approval for Lu-177 dotatate (Lutathera) for patients with advanced NETs in the pancreas or digestive tract. This therapy is also called peptide receptor radionuclide therapy, or PRRT

Learn more about how we use nuclear medicine to treat NETs.


When NETs spread, they often spread to the liver. If the cancer can't be removed with surgery, it may be treated with embolization. This procedure is minimally invasive. Doctors use a catheter (thin tube) to deliver tiny beads into blood vessels in your liver. The beads block the blood supply to the tumors, starving them of oxygen. This shrinks or slows their growth.


Radioembolization is another minimally invasive way to treat NETs in the liver. Doctors use a catheter to deliver tiny beads into blood vessels in your liver. The beads contain radioactive particles. They block the blood supply to the tumors, starving them of oxygen. They also deliver radiation directly to the tumors to shrink or slow their growth.


Chemotherapy medications fight cancer cells by preventing them from growing or dividing. Chemo is usually given as pills or by IV. It can be used before surgery to shrink a tumor or after surgery to kill any cancer cells that remain.

Clinical trials

We are running clinical trials to test promising treatments for NETs. Ask your doctor for more information.

Neuroendocrine tumors team

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