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Overview

What Is a Neuroendocrine Tumor?

A neuroendocrine tumor (NET) is a growth that begins in neuroendocrine cells. These cells receive signals from the nervous system and make hormones that help control body functions. NETs may be benign or cancerous, and they can grow slowly or behave aggressively. A Neuroendocrine Tumor can develop in several organs, including the digestive tract, pancreas, lungs and other parts of the body.

Symptoms

Neuroendocrine Tumor Symptoms

Some neuroendocrine tumor symptoms are absent at first, and the tumor may be found during imaging or testing for another reason. When symptoms occur, they may result from hormones released by the tumor or from its size and location. Not every person has both types of symptoms.

  • Facial flushing.
  • Diarrhea.
  • Wheezing.
  • Low blood sugar (hypoglycemia).
  • Unexplained episodes of sweating.
  • Rapid heartbeat (palpitations).
  • Persistent abdominal pain.
  • A change in bowel habits.
  • Jaundice, or yellowing of the skin and eyes.
  • Cough.
  • Difficulty breathing.
  • A feeling of fullness or pressure caused by tumor growth.

Causes

Causes of Neuroendocrine Tumors

Neuroendocrine tumors begin when neuroendocrine cells acquire DNA changes that allow them to grow and divide without normal controls. In most cases, the specific trigger for these changes is not known. The resulting tumor may be a slower-growing neuroendocrine neoplasm or a more aggressive neuroendocrine carcinoma.

Risk Factors

Risk Factors for Neuroendocrine Tumors

  • Older age is associated with a higher likelihood of developing some neuroendocrine tumors.
  • A family history of neuroendocrine cancer or related tumors may increase risk.
  • Multiple endocrine neoplasia type 1 (MEN1) can increase the risk of tumors in endocrine organs.
  • Von Hippel-Lindau disease is an inherited condition associated with certain neuroendocrine tumors.
  • Neurofibromatosis type 1 can be associated with some neuroendocrine tumors.
  • Tuberous sclerosis can increase the risk of certain tumors.
  • A history of an inherited endocrine or tumor syndrome can increase risk for specific tumor types.
  • Certain medical conditions affecting the pancreas, digestive tract or lungs may be associated with particular neuroendocrine tumors.
  • Tumor risk and behavior vary by the organ involved and the type of neuroendocrine carcinoma.
  • Many people with a neuroendocrine tumor have no identifiable risk factor.

Complications

Complications of Neuroendocrine Tumors

  • A growing tumor can cause blockage in the digestive tract or airways.
  • Tumors can cause bleeding from the digestive tract or another affected organ.
  • Spread to the liver can impair liver function.
  • Spread to the lungs can affect breathing.
  • Reduced appetite, diarrhea or digestive problems can lead to malnutrition.
  • A growing tumor can damage the organ where it started or nearby organs.
  • Carcinoid syndrome can cause flushing, diarrhea and other effects from excess hormone release.
  • Prolonged serotonin excess can damage heart valves.
  • Excess hormone production can cause severe low blood sugar (hypoglycemia).
  • Excess hormone production can cause severe high blood sugar (hyperglycemia).
  • Carcinoid crisis can cause a sudden, potentially life-threatening release of hormones.

SEEK URGENT HELP

Recognize a possible hormone-related crisis

Sudden severe flushing, wheezing, breathing difficulty, a very fast or irregular heartbeat, fainting or major blood pressure changes can signal a serious hormone-related crisis. Seek emergency medical care immediately if these symptoms occur.

Diagnosis & Staging

Diagnosis and Staging of Neuroendocrine Tumors

Diagnosis combines symptoms and a physical examination with hormone or biomarker testing when appropriate, imaging and tissue evaluation. A pathology specialist examines a biopsy to determine the tumor type, grade and differentiation. These findings help guide treatment and provide information about the likely behavior of the tumor.

  • CT or MRI scans can show the tumor and assess nearby organs.
  • PET imaging with a suitable tracer can identify tumors or areas of spread.
  • Endoscopy or bronchoscopy may be used when the tumor is in the digestive tract or lungs.
  • Blood or urine tests can measure hormones or other biomarkers.
  • A biopsy provides tissue for microscopic and laboratory analysis.

Differentiation describes how closely the tumor cells resemble normal neuroendocrine cells. Grade reflects how quickly the cells divide and can help indicate how fast the tumor may grow. Staging describes the primary tumor and whether it has spread to lymph nodes or distant organs, while grade and differentiation describe biological behavior. Exact staging rules vary according to the tumor’s site.

Treatment Options

Treatment Options for Neuroendocrine Tumors

OBSERVATION AND SURVEILLANCE

Selected slow-growing tumors may be monitored with regular visits, tests and imaging instead of treated immediately.

SURGERY AND LOCAL PROCEDURES

Surgery may remove a localized tumor, while endoscopic or other local procedures may treat tumors that are accessible and appropriate for these approaches.

LIVER-DIRECTED TREATMENTS

When NETs have spread to the liver, treatments directed at liver tumors may reduce tumor burden or control symptoms.

HORMONE CONTROL

Somatostatin analogs and other medicines can slow some tumors and reduce hormone-related symptoms.

RADIOLIGAND THERAPY

Peptide receptor radionuclide therapy delivers radiation to NET cells that carry suitable receptors.

TARGETED THERAPY AND CHEMOTHERAPY

Targeted medicines or chemotherapy may be used for selected advanced, progressive or aggressive tumors.

Outlook and Prognosis

Outlook and Prognosis

The outlook ranges from cure after removal of a localized, slow-growing tumor to long-term management or life-threatening illness in aggressive or widely spread disease. A neuroendocrine cancer prognosis cannot be determined from the tumor name alone because NETs vary widely in behavior.

  • Stage, including whether the tumor has spread, strongly affects prognosis.
  • Grade helps indicate how quickly the tumor may grow.
  • Differentiation shows how closely the cells resemble normal neuroendocrine cells.
  • The primary tumor location influences expected behavior and treatment options.
  • Hormone production can affect symptoms and complications.
  • Liver involvement can influence treatment choices and outlook.
  • Overall health affects a person’s ability to tolerate treatment.
  • Response to treatment helps shape the long-term outlook.

Survivorship & Follow-up

Survivorship and Follow-up

Follow-up is often long term because NETs can recur or progress slowly, even after treatment. The schedule depends on the tumor site, stage, grade, treatment and ongoing hormone-related symptoms. Regular care also helps manage treatment effects and support quality of life.

  • Clinical visits help review recovery, new symptoms and overall health.
  • Symptoms and hormone levels may be monitored when the tumor produces hormones.
  • Periodic imaging can check for recurrence or progression.
  • The care team assesses treatment effects and manages complications.
  • Surveillance looks for recurrence or progression over time.