But what are neuroendocrine cells and what do they do?
Our bodies are made up of billions of cells – each with their own appearance and function, for example, blood cells, bone cells, neuroendocrine cells.
Neuroendocrine cells are present throughout our bodies and create a network to keep us well by monitoring what is happening within our bodies and communicating with each other to release specific substances such as gut hormones and/or peptides to help our bodies function normally.
This network is the Neuroendocrine System or the Diffuse Endocrine System.
The type of peptides or hormones neuroendocrine cells release depends on what part of the body they are in, for example:
- In the digestive system they produce hormones that help to break down food in our gut and move food through the small and large bowel – helping both nutritional uptake and eliminating waste.
- In the respiratory system they produce hormones that help with the development of our lungs and to regulate breathing.
- In the brain they produce hormones such as oxytocin (which not only plays a role in breastfeeding, but also social bonding) and melatonin (produced in the pineal gland – and helps regulate our sleep-wake pattern).
- In the adrenal glands they produce the hormones that control our ‘fight or flight response’ – which can affect blood pressure, heart rate and may make us feel anxious.
Cancer of the Neuroendocrine System can therefore produce a number of different symptoms or, in fact, none at all – it all depends on which neuroendocrine cells are affected and how abnormal they have become in terms of size, position and hormone/peptide production.
More recently, a new term has been proposed and is now being used, though mostly in medical publications – Neuroendocrine Neoplasm (neoplasm means new growth) – in practice, you may still hear the words ‘carcinoid’ and ‘NET’ mentioned.
Neuroendocrine Neoplasm, or NEN, has been introduced as the new umbrella term to help clarify the differences between all abnormal growths of the neuroendocrine system – benign or malignant – that is whether they are cancer or not.
For example, adenomas are benign (not cancer) but can occur in neuroendocrine cells.
More importantly, this new term is to help distinguish between the two specific types of neuroendocrine cancer (malignant): NET and NEC – and also clarify how the historical term ‘Carcinoid’ is best used:
- NET (Neuroendocrine Tumor) is cancer starting within neuroendocrine cells that have abnormal changes, that are called ‘well-differentiated’
- NEC (Neuroendocrine Carcinoma) – cancer starting within neuroendocrine cells that have abnormal changes, that are called ‘poorly differentiated’
Both have variable rates of growth, with NET more likely to show slow to moderate growth and NEC more likely to grow rapidly.
- NEN (Neuroendocrine Neoplasm) refers to both of the above, but may also include non-cancer neuroendocrine cell abnormalities.
- Carcinoid (from the German word Karzinoide – meaning cancer-like), is a very old term that is slowly being phased out, but WILL still be used for certain sub-types of Neuroendocrine Cancer e.g. Typical and Atypical Carcinoids of the lung. It is also still used to describe specific Neuroendocrine Cancer related conditions e.g. Carcinoid Syndrome.
The terminology can be confusing and old wording may still be used, even by experts!
So, in brief…
- The Neuroendocrine System is made up of specific cells that help regulate normal bodily functions
- Neuroendocrine Neoplasm or NEN is a new umbrella term that includes neuroendocrine cancer
- NET or Neuroendocrine Tumor is now used for Neuroendocrine Cancer cells, that under a microscope, are described as well-differentiated
- NEC or Neuroendocrine Carcinoma is the term for Neuroendocrine Cancer cells, that under a microscope, are described as poorly-differentiated