The short answer
Neuroendocrine tumors (NETs) are uncommon growths that start in hormone-producing cells found throughout the body, often in the digestive tract, pancreas, or lungs. Many grow slowly. Some release hormones that cause symptoms like flushing or diarrhea, while others cause none. Treatment ranges from surgery to targeted therapies.
NETs start in hormone-making (neuroendocrine) cells found around the body.
They often occur in the digestive tract, pancreas, or lungs.
Many grow slowly, though some are more aggressive.
Some release hormones causing symptoms like flushing or diarrhea.
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The full explanation.
What neuroendocrine tumors are
Neuroendocrine tumors, or NETs, are uncommon growths that begin in neuroendocrine cells — cells that make hormones and are scattered throughout the body. They most often arise in the digestive tract (including the stomach and intestines), the pancreas, and the lungs, but can occur elsewhere.
How they behave
NETs vary widely. Many are slow-growing and may be present for a long time before they are found; others grow more quickly. Doctors describe them by where they start, their grade (how fast the cells divide), and whether they make excess hormones.
Functioning vs non-functioning
Some NETs are functioning, meaning they release hormones that cause symptoms — for example, flushing, diarrhea, wheezing, or low blood sugar. Others are non-functioning and cause no hormone symptoms, often being found incidentally or when they grow large enough to press on something. This variety is why symptoms can be subtle or absent.
Diagnosis and treatment
Diagnosis can involve blood and urine tests for hormones, specialized imaging, and a biopsy. Treatment depends on the type, location, grade, and stage, and may include surgery, hormone-based medicines that control symptoms and slow growth, targeted therapy, and other options. Because NETs are uncommon, care at a center experienced with them is valuable.
Words to know
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Common questions
▸What are neuroendocrine tumors?
Uncommon growths that start in hormone-making cells found throughout the body, often in the digestive tract, pancreas, or lungs.
▸Are NETs slow-growing?
Many are slow-growing, though some are more aggressive. Grade and stage help describe how a particular NET behaves.
▸Why do some cause symptoms and others not?
Functioning NETs release hormones that cause symptoms like flushing or diarrhea, while non-functioning NETs cause no hormone symptoms.
▸How are they treated?
Depending on type and stage, treatment can include surgery, hormone-based medicines, targeted therapy, and other options, ideally at an experienced center.
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