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Types of neuroendocrine tumours

Pathology refers to the examination of tissue under a microscope to find out whether it's cancerous or non-cancerous and to determine the type and nature of the tumour. A tumour of the neuroendocrine system can be benign, potentially malignant or malignant. This is determined by the tumour’s ability to spread to different sites, rate of growth and degree of differentiation (how abnormal the cells look under a microscope.

Neuroendocrine tumours (NETs) are generally slow growing and can be functional (they produce hormones) or non-functional (they do not produce hormones).

Neuroendocrine tumours of the diffuse neuroendocrine system

The diffuse neuroendocrine system is formed by neuroendocrine cells that are scattered throughout the body, but are mainly found in the digestive system and respiratory system.

Gastrointestinal and pancreatic neuroendocrine tumours and carcinomas

Gastrointestinal and pancreatic neuroendocrine tumours are together called gastroenteropancreatic (GEP) neuroendocrine tumours. This is the largest group of neuroendocrine tumours and includes:

  • well-differentiated neuroendocrine tumours
  • well-differentiated neuroendocrine carcinoma
  • poorly differentiated neuroendocrine carcinoma

They can develop in the following areas of the gastrointestinal tract:

  • pancreas
  • small intestine
  • appendix
  • large intestine (colon and rectum)
  • stomach
  • esophagus (rare site of neuroendocrine tumours)

Gastrointestinal and pancreatic neuroendocrine tumours and carcinomas are named based on the type of cell they develop in and the hormones the tumours produce:

  • serotonin-producing neuroendocrine tumours or carcinomas
  • insulinoma
  • gastrinoma
  • VIPoma
  • glucagonoma
  • somatostatinoma
  • ACTHoma
  • PPoma
  • non-functioning

Lung neuroendocrine tumours or carcinomas

Lung neuroendocrine tumours and carcinomas are the second largest group of neuroendocrine tumours. They include the following:

  • typical carcinoid tumours
  • atypical carcinoid tumours
  • small cell carcinoma
  • large cell neuroendocrine carcinoma

Rare neuroendocrine tumours of the diffuse neuroendocrine systen

These include:

Neuroendocrine tumours of the endocrine system

These tumours start in the neuroendocrine cells of various endocrine glands:

Neuroendocrine tumours of unknown primary

Most people diagnosed with neuroendocrine carcinoma of unknown primary (CUP) have advanced disease. They will need aggressive treatment to reduce the tumours as much as possible.

Rarely, neuroendocrine carcinomas can occur elsewhere in the body, including the breast, kidney, urinary bladder and prostate. Other rare neuroendocrine disorders include multiple endocrine neoplasia (MEN) syndromes — genetic disorders that usually cause multiple tumours to develop in the endocrine glands

Once the type of tumour has been diagnosed, the doctor will also consider:

  • the functional status (if the tumour is releasing hormones or not) and type of hormone released
  • the frequency and severity of symptoms caused by too much of a particular hormone
  • the grade of the tumour (how abnormal the cancer cells look and behave)
  • the stage of the cancer, including if it has spread (metastasized) and where it has spread
  • evidence of any complications, such as carcinoid-related heart disease
  • prognostic factors (special characteristics that might influence the course of the disease)
  • survival statistics for the particular type and stage of cancer

All of this information helps the doctor make a treatment plan.

See a list of questions to ask your doctor about pathology and staging.


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