Neuroendocrine Cells and Tumours
Neuroendocrine cells have features of both nerve cells and endocrine cells and are found throughout the body. These cells receive messages from nerve cells and then make hormones in response to those messages. They are found in most of your body’s organs and play a vital role in regulating important body functions such as
- Digesting food
- Controlling body temperature
- Controlling blood pressure
- Managing blood sugar
On rare occasions, neuroendocrine cells found in the lungs, stomach, small bowel, colon or pancreas can develop a complex cancer called a neuroendocrine tumour (NET). Although rare, there are many different types of NETs and they often have different names depending on where they originate. For example, gastrointestinal NETs are also sometimes called “carcinoid” tumours; those originating in the pancreas may be called “islet cell tumours”. Merkel cell cancer is a cancer of the neuroendocrine cells in the skin. Some extremely rare NETs are pheochromocytomas and paragangliomas. A rare genetic disorder called multiple neuroendocrine neoplasia (MEN) can also cause tumours in the neuroendocrine system.
NETs are difficult to identify and often are not diagnosed for a long time because they are rare, usually grow slowly and present few symptoms. Usually NETs produce only vague symptoms such as fatigue and these are often confused with other health problems. Some NETs have no symptoms at all depending on what type of tumour they are. NETs are classified as either “functioning” or non-functioning” depending on whether they make hormones or not. “Functioning” tumours make the same hormones they would if they were healthy cells but they make more than the body needs. These extra hormones can cause symptoms such as diarrhea, flushing, fatigue, shortness of breath and high blood pressure. “Non-functioning” tumours do not make hormones so usually there are no symptoms.
Causes and Risk Factors
In most cases the cause of a NET is unknown, although sometimes there is a hereditary link. For any illness, risk factors are those aspects of a person’s life that may increase the odds that they will become sick. Most risk factors do not directly cause an illness, but seem to be related in some way. While many risk factors are not changeable (such as gender and race), if you have some other risk factors, you may want to talk to your doctor about health care choices you can make to reduce your risk.
Risk factors related to the development of a NET include the following :
- Age: Merkel cell cancer is most common in those over 70 years old.
- Gender: Men are more likely to develop Merkel cell cancer than women are.
- Race/ethnicity: Fair-skinned people are most likely to develop Merkel cell cancer.
- Family history: MEN1 and MEN2 are both hereditary conditions. Ten per cent (10%) of pheochromocytomas are linked to hereditary causes.
- Immune system suppression: People with human immunodeficiency virus (HIV), leukemia and those who have had an organ transplant have suppressed immune systems and are more likely to develop a NET.
- Arsenic exposure: Exposure to arsenic may increase the risk of Merkel cell cancer.
- Sun exposure: Because Merkel cell cancer often occurs on areas of skin that are usually exposed to the sun, it is possible that sun exposure is a risk factor.
The doctor may order some or all of the following tests to find and treat a neuroendocrine tumour:
- Blood and urine analysis
- Scans – some of these tests require the patient to either drink or receive by IV a contrast fluid
- CT scan
- Magnetic Resonance Imaging (MRI) scan
- FDG PET scan
- Octreotide imaging
- 123I-mIBG imaging
After reviewing your test results, your doctor will talk to you about which treatment option is most appropriate for you. There are 3 active treatment options.
- Surgery is planned if the tumour is found early enough and/or if the tumour is easy to reach
- Radioisotope therapy involves the patient receiving radioactive material either by mouth or through an IV. The cancer cells absorb this radioactive substance and are destroyed.
- Drug treatments may be used to help control symptoms, such as diarrhea. Other drugs may be given in order to shrink, remove or stop the growth of the tumour.
Neuroendocrine Tumour Clinic at the Cross Cancer Institute
The Cross Cancer Institute in Edmonton is home to the only clinic in western Canada offering radio iodine treatment in the treatment of NETs. Click HERE to read an article about nurse Karey McCann, who has been nationally recognized for her management of the Neuroendocrine Tumour Clinic.
Neuroendocrine diseases treated at the Northern Alberta Endocrine Surgery Centre include the following:
- Multiple endocrine neoplasia (MEN-1, MEN-2A, MEN-2B)
- Familial pheochromocytoma/panganglioma syndromes