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
- well-differentiated neuroendocrine tumours
- well-differentiated neuroendocrine carcinoma
- poorly differentiated neuroendocrine carcinoma
They can develop in the following areas of the gastrointestinal tract:
- small intestine
- large intestine (colon and rectum)
- 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
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
- Merkel cell carcinoma
- neuroendocrine carcinoma of the larynx
Neuroendocrine tumours of the endocrine system
These tumours start in the neuroendocrine cells of various endocrine glands:
- pituitary adenoma - tumours in the pituitary gland
- thyroid medullary carcinoma - starts in neuroendocrine C cells of the thyroid gland
- thymus neuroendocrine cancer - starts in cells of the thymus
- parathyroid neuroendocrine cancer - starts in the parathyroid glands, which are part of the endocrine systemendocrine systemThe group of glands and cells in the body that make and release hormones (which control many functions such as growth, reproduction, sleep, hunger and metabolism) into the blood.
- pheochromocytoma - starts in the specialized nerve cells found in the adrenal medulla
- paraganglioma – starts in specialized nerve cells called paraganglia
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.