Neuroendocrine tumours (NETs) are abnormal growths that arise from neuroendocrine cells. Neuroendocrine cells have features of nerve cells and endocrine (hormone-producing) cells, and can occur anywhere in the body.
NETs are rare and typically appear in the gastrointestinal tract, pancreas and bronchi, but also in other areas of the body. The most common neuroendocrine tumour is one that occurs in the intestine, often known as a carcinoid tumour.
Dr Florian Wernig, leading consultant endocrinologist from London, walks us through the typical symptoms of NETs and what your treatments options are if you have received a diagnosis.
What are the symptoms of a neuroendocrine tumour (NET)?
The most common neuroendocrine tumour (NETs) is a carcinoid tumour, which is a slow-growing type of cancer. The symptoms depend on where in the body the tumour is and which hormones it produces. Carcinoid tumours that arise in the digestive system may cause diarrhoea, and/or abdominal pain. They can release hormones such as serotonin which can lead to carcinoid syndrome, resulting in flushing, diarrhoea, excessive sweating, bronchoconstriction and hypotension.
While these symptoms can occur in some people, most carcinoid tumours are asymptomatic - fewer than 10% of NETs actually produce symptoms. Most often, NETs are only noticed on scans, such as abdominal computed tomography (CT) when a patient presents for another condition.
How are neuroendocrine tumours treated?
Over the last few years, several new treatments have emerged to reduce the tumour bulk of carcinoid and other NETs.
Once a patient has been newly diagnosed, the most important element of management is to refer them to a specialist multidisciplinary team to evaluate the following:
- The tumour grade (the pace of progression)
- The stage of the cancer (the extent and burden of the disease)
- Tumour functionality (hormone secretion by the tumour)
- Which medical, surgical and/or radiotherapeutic treatments are best suited to the patient
There are many different treatment options available:
Surgical removal of the tumour and surrounding healthy tissue during an operation is potentially curative, especially for gastrointestinal NETs. It is thought that around 20% of patients will be cured following this surgery. If a tumour cannot be completely removed, surgery is sometimes performed to remove as much tumour as possible in order to make subsequent treatments more effective.
Somatostatin analogue injections
These injections can help slow the growth of neuroendocrine tumour cells. They can be especially helpful for certain patients with pancreatic NETs as the drug can stop the tumour from releasing hormones into the bloodstream - relieving symptoms and helping patients to feel better.
Non-surgical methods of ‘debulking’ (reduction of tumour burden)
There are many well-established and emerging techniques that can be used on patients who have a tumour that has spread to other areas of the body and in whom surgical treatment has been previously ineffective or not suitable. This includes:
- Radiofrequency ablation (RFA) - By using a radiologically-guided probe inserted into the tumour, radiofrequency waves can increase the temperature within the tumour tissue and kill the cancerous cells.
- Trans-arterial embolisation (TAE) - Blood supply to the tumour is blocked to kill the cancer cells. It can provide effective treatment for patients who have predominantly liver disease.
- Selective internal radiation therapy with Yttrium-90-labelled microspheres (SIRT) - Involves the use of targeted radiation to kill cancer cells in the liver.
Peptide receptor radionuclide therapy (PRRT)
PRRT has emerged over the last 10 years as a significant treatment option for NETs. It is a molecular-targeted therapy that uses a radionuclide such as Lutetium-177 combined with a peptide similar to the naturally-occurring hormone somatostatin to identify and attack neuroendocrine cancer cells while mostly avoiding healthy tissue.
It is a relatively new technique and trials have shown it can significantly improve symptoms and the patients’ chance of progression-free survival as well as possibly overall survival. PRRT is usually well-tolerated with relatively few and mild side effects only.
NETs that originate in the small bowel don’t usually respond well to chemotherapy. However, chemotherapy would often be the treatment of choice for poorly differentiated (fast-growing) neuroendocrine tumours. There are also several novel targeted chemotherapy agents which have proved effective in treating progressive pancreatic NETs. This includes everolimus, sunitinib and bevacizumab.
To make an appointment with Dr Florian Wernig, visit his Top Doctors profile and check his availability.