How are neuroendocrine tumours (NETs) treated?

Surgery is usually the first choice for treatment if imaging scans show that the primary tumour is contained in one area (localised) or there has been only limited spread within an organ of the body. If it is possible to remove the tumour completely with surgery then no other treatment may be necessary.

Even if the primary tumour has spread (metastasised), surgery may still be possible to remove part of the tumour and any other secondary tumours.

If GEP-NETs or other NETs are blocking an organ, such as the bowel, then surgery may be helpful to relieve the blockage. If the tumour has spread to the liver, surgery can be used to remove the parts of the liver containing the tumour. Very occasionally, a liver transplant may be considered.

Somatostatin analogues are medications that copy the action of natural somatostatin.

Somatostatin is a hormone – a chemical messenger that is naturally produced in the body. It can stop the over-production of other hormones that cause neuroendocrine cancer symptoms, such as diarrhoea, flushing and wheezing.

Somatostatin analogues may reduce symptoms of NETs by stopping the body from making too many hormones. They may also control the growth of certain types of NETs.

When you start using a somatostatin analogue, you may be given an injection of the product up to three times a day or you may receive a longer-acting injection that can last for a month or so.

Molecular targeted therapy involves the administration of drugs or other substances that block the growth, development and spread of cancer cells. They do this by interfering with the activity of specific molecules involved in the process by which normal cells become cancer cells, and how tumours grow and develop their own blood supply.

The drugs that used are used target specific biological differences between cancer cells and normal cells and some can target the cancer cells without harming the normal cells.

Molecular targeted therapies can be taken as tablets and may be prescribed to some people with NETs, most of them having first received somatostatin analogue medications.

Targeted radionuclide therapy is also called peptide receptor radionuclide therapy (PRRT) or hormone-delivered radiotherapy. PRRT is based on using radioactive substances (radionuclides) to target receptors on the tumour cells’ surface.

In this type of treatment for NETs, radionuclides are chemically combined with hormones (somatostatin analogues). When this combination treatment is injected into the body, it will fix on the surface of the neuroendocrine cancer cells and deliver a targeted radiation dose to prevent further tumour growth or even destroy the tumour.

Chemotherapy involves the use of anti-cancer (cytotoxic) drugs to destroy cancer cells, usually by stopping the cancer cells’ ability to grow and divide. Systemic chemotherapy is delivered through the bloodstream to reach neuroendocrine cancer cells within the body.

Common ways to give chemotherapy include the use of a thin tube (catheter) placed into a vein using a needle (intravenous delivery) or via an oral pill or capsule.

The type of chemotherapy that you are given will depend on where in the body the NETs started.

For example, some people may receive chemotherapy to treat NETs in the pancreas (pancreatic NETs) or lungs (bronchial NETs). Chemotherapy can be used alone to treat NETs, or together with other treatments and procedures overviewed in this section.

Interferon is a naturally occurring substance that is produced by the body’s immune system during an illness such as a viral infection, such as influenza.

Interferon is sometimes called biologic therapy or immunotherapy and is used to treat some people with NETs.

Sometimes interferon is taken on its own as a medication for NETs.

However, it is often taken as part of a combination therapy with somatostatin analogues. Interferon may not be a suitable therapy for everyone with NETs.

Although radiation therapy is used to treat a wide range of cancers, it is only an option in selected cases of NETs. For example, it is particularly helpful in alleviating pain caused by bone metastases.

Radiation therapy uses high-energy particles or waves, such as X-rays, gamma rays, electron beams, or protons, to destroy or damage cancer cells.

Before radiotherapy can be given, imaging scans will be performed to determine the precise location of the tumours.

Radiation therapy aims to give the highest chance of shrinking the cancer, and the lowest doses to surrounding healthy cells to avoid treatment side effects.

Other names for radiation therapy are radiotherapy, irradiation, or X-ray therapy.

External beam radiotherapy is given to cancer patients as a series of short, daily external treatments, typically for several weeks but in the treatment of bone metastases the duration of treatment is usually much shorter.

It uses equipment similar to a large X-ray machine called a linear accelerator. Each of these short treatments is called a fraction. Giving external beam therapy in fractions means that less damage is done to normal cells than to cancer cells.

Other treatment options are currently under clinical development and may become available in the future. Please note such treatments are not yet approved, and there is a possibility they may never be approved and available in your country.

Besides interferon there are other drugs and approaches being developed to specifically use the body’s immune system to attack cancer cells:

• One approach is the use of laboratory-made antibodies that can recognise that a cell is cancerous and destroy it without harming the body’s normal cells.

• Another approach is to take some of a person’s blood, separate out a specific white blood cell type called a T-cell, adapt it in the laboratory and then put it back into the same patient. The adapted T-cells then attack the cancer cells more specifically while leaving normal cells alone.
• Immunotherapies are drugs which can switch the body’s immune system ‘on’ to kill cancer cells. It is used in other cancers but is being tested in NETs.