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Pancreatic Neuroendocrine Tumor (NET)
Having one or more of the symptoms below does not mean you have a pancreatic neuroendocrine tumor (NET). In fact, many of these symptoms are more likely to be caused by other conditions. Still, if you have any of these symptoms, it’s important to have them checked by a doctor so that the cause can be found and treated, if needed.
Pancreatic NETs often release excess hormones into the bloodstream. Different types of tumors make different hormones, which can lead to different symptoms.
These tumors make gastrin, a hormone that tells the stomach to make more acid. Too much gastrin causes a condition known as Zollinger-Ellison syndrome, in which the stomach makes too much acid. This leads to stomach ulcers, which can cause pain, nausea, and loss of appetite. Severe ulcers can bleed. Even if the bleeding is mild, it can lead to anemia (too few red blood cells), which can cause symptoms like feeling tired and being short of breath. If the bleeding is more severe, it can make stool black and tarry. Severe bleeding can itself be life-threatening.
If the stomach acid reaches the small intestine, it can damage the cells of the intestinal lining and break down digestive enzymes before they have a chance to digest food. This can cause diarrhea and weight loss.
These tumors make glucagon, a hormone that increases glucose (sugar) levels in the blood. Most of the symptoms that can be caused by a glucagonoma are mild and are more often caused by something else.
Excess glucagon can raise blood sugar, sometimes leading to diabetes. This can cause symptoms such as feeling thirsty and hungry, and having to urinate often.
People with these tumors can also have problems with diarrhea, weight loss, and malnutrition. The nutrition problems can lead to symptoms like irritation of the tongue and the corners of the mouth.
The symptom that brings most people with glucagonomas to their doctor is a rash called necrolytic migratory erythema. This is a red rash with swelling and blisters that often travels from place to place on the skin.
These tumors make insulin, which lowers blood glucose levels. Too much insulin leads to low blood sugar, which can cause symptoms like weakness, confusion, sweating, and rapid heartbeat. When blood sugar gets very low, it can lead to a person passing out or even going into a coma and having seizures.
These tumors make somatostatin, which helps regulate other hormones. Symptoms of this type of tumor can include belly pain, nausea, poor appetite, weight loss, diarrhea, symptoms of diabetes (feeling thirsty and hungry, and having to urinate often), and jaundice (yellowing of the skin and eyes).
The early symptoms of a somatostatinoma tend to be mild and are more often caused by other things, so these tumors tend to be diagnosed at an advanced stage. Often, they are not found until they spread to the liver, when they cause problems like jaundice and pain.
These tumors make a substance called vasoactive intestinal peptide (VIP). Too much VIP can lead to problems with diarrhea. This may be mild at first, but gets worse over time. By the time they are diagnosed, most people have severe, watery diarrhea.
Other symptoms can include nausea, vomiting, muscle cramps, feeling weak or tired, and flushing (redness and warmth in the face or neck).
People with these tumors also tend to have low levels of acid in their stomachs, which can lead to problems digesting food.
These tumors often make serotonin or its precursor, 5-HTP. Carcinoid tumors often don’t cause symptoms until they spread outside the pancreas. When these tumors do spread, it is most often to the liver. There, the cancer cells can release hormones directly into the blood. This can cause the carcinoid syndrome, with symptoms including flushing (redness and warmth in the face or neck), diarrhea, wheezing, and a rapid heart rate. These symptoms often occur in episodes, between which the person may feel fine.
Over a long time, the hormone-like substances released by these tumors can damage heart valves, causing shortness of breath, weakness, and a heart murmur (an abnormal heart sound).
These tumors don’t make excess hormones, so they don’t cause symptoms in early stages and often grow quite large before they are found. Most of these start to cause problems as they get larger or spread outside the pancreas. Symptoms can be like those from exocrine pancreas cancers, including jaundice (yellowing of the eyes and skin), belly pain, and weight loss. Sometimes, as a pancreatic NET grows, it can go from making too little of a hormone (nonfunctioning) to making too much of a specific hormone (functioning) which causes symptoms.
When pancreatic NETs spread, most often they go to the liver. This can enlarge the liver, which can cause pain and loss of appetite. It can also affect liver function, sometimes leading to jaundice (yellowing of the skin and eyes) and abnormal blood tests.
These cancers can also spread to other organs and tissues. The symptoms depend on where the cancer is growing. For example, cancer spread to the lungs can cause shortness of breath or a cough. Spread to bones can cause pain in those areas.
The American Cancer Society medical and editorial content team
Our team is made up of doctors and oncology certified nurses with deep knowledge of cancer care as well as journalists, editors, and translators with extensive experience in medical writing.
National Cancer Institute. Physician Data Query (PDQ). Pancreatic Neuroendocrine Tumors (Islet Cell Tumors) Treatment – Patient Version. 2018. Accessed at https://www.cancer.gov/types/pancreatic/patient/pnet-treatment-pdq on October 1, 2018.
National Comprehensive Cancer Network. NCCN Clinical Practice Guidelines in Oncology: Neuroendocrine and Adrenal Tumors. V.2.2018. Accessed at https://www.nccn.org/professionals/physician_gls/pdf/neuroendocrine.pdf on October 2, 2018.
Schneider DF, Mazeh H, Lubner SJ, Jaume JC, Chen H. Chapter 71: Cancer of the endocrine system. In: Niederhuber JE, Armitage JO, Dorshow JH, Kastan MB, Tepper JE, eds. Abeloff’s Clinical Oncology. 5th ed. Philadelphia, Pa. Elsevier: 2014.
Strosberg JR. Classification, epidemiology, clinical presentation, localization, and staging of pancreatic neuroendocrine neoplasms. UpToDate website. https://www.uptodate.com/contents/classification-epidemiology-clinical-presentation-localization-and-staging-of-pancreatic-neuroendocrine-neoplasms. Updated Jan. 23, 2018. Accessed October 2, 2018.
Last Revised: October 30, 2018
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