Neuroendocrine Tumors
Tumors of hormone-producing cells in the body
Quick Facts
- Type: Tumors of neuroendocrine cells
- Common sites: Gut, pancreas, lungs
- Behavior: Slow-growing to aggressive
- Some types: Release excess hormones
Overview
Neuroendocrine tumors, often called NETs, are growths that begin in neuroendocrine cells. These specialized cells are scattered throughout the body and share features of both nerve cells and hormone-making gland cells. They are most common in the digestive tract, pancreas, and lungs, but they can occur in many organs.
Neuroendocrine tumors vary greatly in behavior. Some grow very slowly over many years and cause few problems, while others are aggressive and spread more quickly. Some NETs are called functional because they release hormones that cause distinct symptoms, while others are non-functional and may grow silently until they press on nearby structures. Because of this wide range, treatment and outlook are highly individual.
Symptoms
Many neuroendocrine tumors cause no symptoms early on and are found by chance. When symptoms occur, they depend on the tumor's location and whether it releases hormones.
- Flushing of the skin, especially on the face and neck
- Diarrhea or changes in bowel habits
- Wheezing or shortness of breath
- Abdominal pain or a feeling of fullness
- Low blood sugar episodes with shakiness or confusion, with certain pancreatic NETs
- Unintended weight loss or fatigue
Hormone-related symptoms can come and go, which sometimes delays diagnosis.
Causes
In most cases the exact cause of a neuroendocrine tumor is not known. The tumors arise when neuroendocrine cells undergo genetic changes that cause them to grow out of control. Most NETs occur sporadically, without a clear inherited cause.
A small number are linked to inherited genetic syndromes that increase the risk of tumors in hormone-producing tissues. People with these syndromes may develop NETs at a younger age or in more than one site, which is why family history can be relevant.
Risk Factors
- Inherited syndromes affecting hormone-producing glands, such as multiple endocrine neoplasia
- A family history of neuroendocrine tumors
- Older age, for many types
- Certain other genetic conditions that raise tumor risk
Diagnosis
Diagnosing a neuroendocrine tumor often involves several steps because the tumors can be small and slow to declare themselves.
- Blood and urine tests: To measure hormones or markers that some NETs release.
- Imaging: CT, MRI, and specialized scans that target neuroendocrine cells help locate tumors and check for spread.
- Biopsy: A tissue sample examined under the microscope confirms the diagnosis and shows how fast the tumor is growing (its grade).
- Endoscopy: Used to find and sample tumors in the digestive tract or lungs.
Treatment
Treatment depends on the tumor's location, grade, whether it has spread, and whether it makes excess hormones.
- Surgery: Removing the tumor offers the best chance of cure for localized NETs.
- Hormone-blocking medicines: Drugs that slow tumor growth and control hormone-related symptoms.
- Targeted therapy and chemotherapy: Used for tumors that have spread or grow more quickly.
- Specialized radiation therapies: Treatments that deliver radiation directly to neuroendocrine tumor cells.
- Supportive care: To manage symptoms and maintain quality of life.
Because some NETs grow slowly, careful monitoring may sometimes be chosen over immediate treatment.
Prevention
Most neuroendocrine tumors cannot be prevented because their cause is unknown. Sensible steps include:
- Knowing your family history and sharing it with your doctor
- Considering genetic counseling if a hereditary syndrome runs in your family
- Attending recommended surveillance if you have a known risk syndrome
- Reporting persistent flushing, diarrhea, or unexplained symptoms for evaluation
When to See a Doctor
See a doctor if you have persistent flushing, diarrhea, wheezing, abdominal pain, or unexplained weight loss, especially if these symptoms come and go over weeks or months. Seek urgent care for:
- Severe or sudden abdominal pain
- Episodes of confusion, sweating, or fainting from low blood sugar
- Severe difficulty breathing
Frequently Asked Questions
Are neuroendocrine tumors cancerous?
Neuroendocrine tumors range from slow-growing growths with low spread potential to aggressive cancers. Whether a tumor behaves more like a benign growth or a fast-spreading cancer depends on its grade and stage, which a biopsy and imaging help determine.
What is a functional neuroendocrine tumor?
A functional NET releases excess hormones that cause specific symptoms, such as flushing, diarrhea, or low blood sugar. A non-functional NET does not produce noticeable hormone effects and may grow quietly until it presses on nearby organs.
What is carcinoid syndrome?
Carcinoid syndrome is a set of symptoms, such as facial flushing, diarrhea, and wheezing, caused by hormones released from certain neuroendocrine tumors. It usually appears when the tumor has spread, often to the liver.
How are neuroendocrine tumors treated?
Treatment may include surgery to remove the tumor, hormone-blocking medicines, targeted therapy, chemotherapy, and specialized radiation treatments. The plan depends on the tumor's location, grade, and whether it has spread, and slow-growing tumors are sometimes monitored closely.
Can neuroendocrine tumors run in families?
Most occur sporadically, but a small number are linked to inherited syndromes that increase the risk of tumors in hormone-producing glands. If NETs or related tumors run in your family, genetic counseling may be worthwhile.
References
- National Cancer Institute (NCI). Gastrointestinal neuroendocrine tumors.
- Mayo Clinic. Neuroendocrine tumors.
- MedlinePlus, U.S. National Library of Medicine. Neuroendocrine tumors.
- American Cancer Society. Neuroendocrine tumors.