You are here: 

Pancreatic neuroendocrine tumours and carcinomas

Pancreatic neuroendocrine tumours (PNETs) are rare, slow-growing tumours. They are also called pancreatic endocrine tumours (PETs) or pancreatic islet cell tumours. Pancreatic neuroendocrine tumours can be either benign or malignant.

Pancreatic endocrine tumours start in the hormonehormoneA substance that regulates specific body functions, such as metabolism, growth and reproduction.-producing cells of the pancreas. They make up about 5% of all pancreatic cancers and are considered more treatable than exocrine pancreatic cancers.

Anatomy and physiology of the pancreas

Pancreatic neuroendocrine tumours are made up of endocrine cells that are usually found in islet cells throughout thepancreas. They make up a small percentage of the pancreas, and are part of the body’s endocrine systemendocrine systemThe group of glands and cells in the body that make and release hormones (which control many functions such as growth, reproduction, sleep, hunger and metabolism) into the blood.. The islet cells produce and release the following hormones into the blood:

  • insulin
    • reduces the amount of sugar (glucose) in the blood
    • stimulates the liver, muscles and fatty tissues to absorb and store the extra sugar
  • glucagon
    • increases the amount of sugar in the blood
    • stimulates the liver and other body tissues to release stored sugar
  • somatostatin
    • slows the release of other hormones produced by the pancreas
  • pancreatic polypeptide
    • regulates the hormones released by the pancreas

Find out more about anatomy of the pancreas.

Risk factors

Most people with PNETs do not have any identifiable risk factors. Rarely, PNETs may be caused by inherited or genetic conditions, such as multiple endocrine neoplasia (MEN) syndromes. Recognizing symptoms and getting regular checkups are the best ways to detect PNETs early. The sooner symptoms are reported, the sooner a doctor can diagnose and treat the cancer.

Signs and symptoms

Pancreatic neuroendocrine tumours cause a variety of signs and symptoms. The majority of tumours are slow-growing and symptoms result from the growth of the tumour and the effects of specific hormones it produces. Many PNETs may be small and non-functional (do not produce hormones), causing no symptoms at all.

Pancreatic neuroendocrine tumours are named for the type of pancreatic hormone that they produce. The types of pancreatic neuroendocrine tumours are:


Insulin-producing tumours are the most common pancreatic neuroendocrine tumour, but only 10% of insulinomas are malignant. They produce too much of the hormone insulin, which reduces the blood sugar (glucose) level. Some insulinoma tumours also secrete other pancreatic hormones.

  • Malignant insulinomas are usually larger than benign tumours, often larger than 6 cm.
  • Multiple tumours are found in about 10% of people diagnosed with insulinoma.

The signs and symptoms of insulinoma are related to low blood sugar (hypoglycemia) and may include:

  • light-headedness and fainting
  • sweating
  • rapid heartbeat and awareness of heart beating (palpitations)
  • changes in behaviour (jittery, nervous, irritable or confused)

With extremely low blood sugar, the person may experience:

  • loss of consciousness
  • seizure
  • coma

Insulinoma tumours are associated with a group of signs and symptoms called Whipple’s triad:

  • low blood sugar (glucose) level
  • symptoms of hypoglycemia
  • giving the person sugar quickly relieves the symptoms and brings the blood sugar back up to normal


Gastrin-producing tumours are the most common malignant pancreatic neuroendocrine tumour. They can also develop in the stomach and first part of the small bowel (duodenumduodenumThe first part of the small intestine that receives partially digested food from the stomach, absorbs nutrients and passes digested food to the jejunum. The duodenum also receives digestive juices from the pancreas and bile (a yellow-green fluid that helps digest fat) from the liver and gallbladder.). Gastrinoma tumours produce too much of the hormone gastrin. Gastrin increases stomach acid production, which can cause peptic ulcers that can bleed and perforate. The signs and symptoms of too much gastrin are known as Zollinger-Ellison syndrome.

  • At the time of diagnosis, most gastrinoma tumours have already spread to other organs (metastasized).
  • Most tumours are larger than 3 cm, and there may be several tumours at the same time.
  • Most gastrinomas are found in the duodenum. The head of the pancreas is the second most common site.

The signs and symptoms of gastrinoma are related to high levels of stomach acid and are similar to those of stomach ulcers:

  • persistent stomach pain
  • severe heartburn, which can lead to
    • inflammation of the esophagusesophagusThe muscular tube in the neck and chest through which food passes from the pharynx (throat) to the stomach.
    • Barrett’s esophagusBarrett’s esophagusA condition in which cells that line the lower part of the esophagus (the tube through which food passes from the throat to the stomach) change into or are replaced by abnormal cells. It may be caused by stomach acid backing up into the esophagus over time (gastroesophageal reflux disease or GERD).
  • severe diarrhea and fatty stools (steatorrhea)
  • bleeding in the stomach
  • vomiting
  • low red blood cell count (anemia)
  • weight loss


VIP-producing tumours are the third most commonly diagnosed type of pancreatic neuroendocrine tumour, but they are very rare. VIPomas produce too much of the hormone vasoactive intestinal peptide (VIP), which increases bowel activity. VIP is normally produced by the cells of the gastrointestinal tract.

  • Almost all VIPomas are malignant. Most people will have metastatic disease at the time of diagnosis.
  • VIPomas are more commonly diagnosed in women.

VIPoma is associated with a group of signs and symptoms called WDHA syndrome (also called Verner-Morrison syndrome or pancreatic cholera):

  • massive amounts of watery diarrhea
  • abnormally low potassium level in the blood (hypokalemia) caused by diarrhea
  • little or no stomach acid (achlorhydria)

Most of the signs and symptoms of VIPoma are caused by the low level of potassium and may include:

  • muscle problems
    • weakness
    • cramping
    • aches
  • lethargylethargyAbnormal drowsiness, lack of energy or severe disinterest in activity.
  • flushing
  • changes in heart rhythm
  • dehydration (caused by the diarrhea)
  • abdominal pain and cramping


Glucagon-producing tumours make up less than 1% of all pancreatic neuroendocrine tumours. Up to 80% of glucagonomas are malignant. Glucagonomas produce too much of the hormone glucagon, which increases blood sugar. They may also overproduce other hormones.

Glucagonoma is associated with a group of signs and symptoms called glucagonoma syndrome:

  • skin rash called necrolytic migratory erythema (NME)
    • red, swollen skin
    • blisters
    • can be itchy and painful
    • most common on legs, groin and buttocks
  • blood clots in the leg (deep vein thrombosis)
  • diarrhea
  • depression

Other signs and symptoms of glucagonoma include:

  • painful or swollen tongue (glossitis)
  • mouth sores (stomatitis)
  • diabetic symptoms
    • unusual thirst
    • frequent urination
    • unusual weight loss
    • extreme fatigue or lack of energy
  • abdominal pain
  • blood clots in the lung (pulmonary embolism)
  • muscle wasting
  • slow speech
  • changes to vision


Somatostatinomas produce too much of the hormone somatostatin, which blocks many of the other hormones produced by the pancreas (insulin, gastrin and glucagon). This very rare pancreatic neuroendocrine tumour is slow growing and is not usually diagnosed early. Almost all somatostatinomas are malignant.

The signs and symptoms of somatostatinoma include:

  • diabetic symptoms
  • gallstones
  • diarrhea and fatty stools (steatorrhea)
  • abdominal pain
  • nausea and vomiting
  • loss of appetite
  • low levels of stomach acid (achlorhydria)

Non-functioning pancreatic neuroendocrine tumours

Non-functioning neuroendocrine tumours may produce hormones, but only in very small amounts. These hormones do not cause symptoms or abnormal blood tests. Some of these tumours have no evidence of hormone production. Approximately 30% of pancreatic neuroendocrine tumours are non-functioning.

  • Almost all non-functioning pancreatic neuroendocrine tumours are malignant.
  • Most people with this type of tumour have metastases at the time of diagnosis.
  • These tumours are commonly diagnosed between the ages of 30 and 40 years.

The signs and symptoms are caused by the growth and spread of the tumour:

  • abdominal pain
  • lump in the abdomen
  • jaundicejaundiceA condition in which the skin and whites of the eyes become yellow and urine is dark yellow.
  • blockage of the small intestine (bowel obstruction)
  • blockage of the bile ducts and gallbladder
  • bleeding of the tumour into the stomach or small intestine

Other rare pancreatic neuroendocrine tumours

There is very little information about these extremely rare types of pancreatic neuroendocrine tumours.


These tumours cause an increase in growth-hormone releasing hormone (GRH), which stimulates the pituitary gland to release growth hormone. Too much growth hormone causes abnormal growth of bones and cartilage. This disorder is called acromegaly.

GRHomas are more commonly diagnosed in women.


These tumours cause an increase in pancreatic polypeptide (PP), which can cause diarrhea.


These tumours cause increased levels adrenocorticotropic hormone (ACTH). This hormone regulates the release of cortisol, a steroid produced by the adrenal glands. ACTHoma causes Cushing’s syndromeCushing’s syndromeA group of symptoms that include high blood pressure, high blood sugar, round face, thin arms and legs, fatigue, muscle weakness and weight gain (which may cause purple stretch marks on the stomach)..

ACTHomas can be very fast-growing and aggressive cancers.


In recent years, the reported incidence of neuroendocrine tumours has increased. This increase may be due to more awareness of the disease and better diagnostic tests.

Find out more about tests used to diagnose and stage neuroendocrine cancer.

Pathology and staging

Different types of neuroendocrine tumours can affect the pancreas. Pancreatic neuroendocrine tumours can be either benign or malignant. They may produce hormones (functioning) or may not produce hormones (non-functioning). Pancreatic neuroendocrine tumours are named according to the type of pancreatic hormone that they overproduce. They may be further classified into the following groups based on the WHO classification:

  • benign or potentially malignant tumours
  • well-differentiated neuroendocrine cancer
  • poorly differentiated neuroendocrine cancer
  • mixed neuroendocrine tumours
  • rare neuroendocrine-like tumours

Staging is a way of describing or classifying a cancer based on the extent of cancer in the body. There is no detailed or generally accepted staging system for pancreatic neuroendocrine tumours. Tumours may be staged in the following general categories:


Localized pancreatic neuroendocrine tumours occur only in one place in the pancreas.


Regionalized pancreatic neuroendocrine tumours occur in several places in the pancreas.


Metastatic pancreatic neuroendocrine tumours have spread to the lymph nodes near the pancreas or to distant sites.


Recurrent pancreatic neuroendocrine tumours have come back after treatment. They may recur in the same location as the original cancer or in another part of the body (metastatic pancreatic neuroendocrine tumours).

Find out more about grading, disease progression and prognosis and survival.


Each person with pancreatic neuroendocrine tumours will have a treatment plan designed for them by their healthcare team. The team will recommend treatment options based on the specific characteristics of the cancer and the unique needs of the person.

Find out more about treatment options for neuroendocrine cancer and their side effects and follow-up after treatment.


Parker Murchison My favourite thing about Camp Goodtime is being able to hang out with other kids who have survived cancer. They know what is going on in your life and can help you get through it.

Read Parker's story

A home away from home

Illustration of house

For cancer patients who must travel a great distance to get to treatment, Canadian Cancer Society lodges offer a welcoming place to stay.

Learn more