Radiation therapy for neuroendocrine tumours (NETs)

Radiation therapy uses high-energy rays or particles to destroy cancer cells. It is not usually used to treat neuroendocrine tumours (NETs). If used, it is usually when the cancer has spread (metastasized). Your healthcare team will consider your personal needs to plan the type and amount of radiation, and when and how it is given. Most people receive other treatments before radiation therapy.

Radiation therapy is given for different reasons. You may have radiation therapy to:

• destroy cancer cells in the body
• destroy cancer cells left behind after surgery or other therapies
• relieve pain or control the symptoms of advanced neuroendocrine cancer (called palliative therapy)

The following types of radiation therapy are used to treat NETs.

Radionuclide therapy (also called internal radiation therapy) uses a radioactive material called a radioisotope that travels through the body. Cancer cells take up the radioactive material, and the radioactive material destroys the cancer cells. For NETs, the radioactive material is usually combined with a substance (a radiopharmaceutical) that targets specific molecules on the surface of cancer cells. Using the radiopharmaceutical allows the radiation to be delivered directly to the cancer cells and limits the effects of radiation on normal cells. Radionuclide therapy may be called targeted radiation therapy or systemic radiation therapy.

PRRT is a type of radionuclide therapy used to treat NETs. It uses a radioactive material, usually lutetium-177 (Lu-177), combined with a somatostatin analogue (octreotide or octreotate). This radiopharmaceutical is given through a needle into a vein (intravenously).

PRRT may be used for well-differentiated NETs when:

• surgery can’t be done
• some cancer remains after surgery or radiofrequency ablation (RFA)
• the cancer has continued to grow (progressed) and spread (metastasized)

PRRT doesn’t work for all NETs because octreotide may not attach to the tumour cells. Most people need an octreotide scan before being considered for PRRT. This scan shows if octreotide attaches to NET cells.

Lutetium-177 octreotate (Lutathera) is a PRRT used to treat unresectable or metastatic, well-differentiated, somatostatin receptor-positive gastroenteropancreatic neuroendocrine tumours that continues to grow and spread.

During external beam radiation therapy, a machine directs radiation through the skin to the tumour and some of the tissue around it. It is not usually used to treat NETs, but it may be given to relieve pain and manage symptoms from bone metastases or brain metastases.

Find out more about bone metastases and brain metastases.

Side effects can happen with any type of treatment for NETs, but everyone’s experience is different. Some people have many side effects. Other people have few or none at all.

During radiation therapy, the healthcare team tries to protect healthy cells in the treatment area as much as possible. For example, an amino acid mixture is given before PRRT to protect the kidneys from the effects of the radioactive material. But damage to healthy cells can happen and may cause side effects.

If you develop side effects, they can happen any time during, immediately after or a few days or weeks after radiation therapy. Sometimes late side effects develop months or years after radiation therapy. Most side effects go away on their own or can be treated, but some side effects may last a long time or become permanent.

Side effects of radiation therapy will depend mainly on the type of radiation used and the treatment schedule. Radionuclide therapy doesn’t usually cause many side effects.

Some common side effects of radiation therapy used for NETs are:

• nausea and vomiting
• low blood cell counts (bone marrow suppression)
• fatigue
• skin problems, including redness and irritation, most often from external beam radiation therapy

Tell your healthcare team if you have these side effects or others you think might be from radiation therapy. The sooner you tell them of any problems, the sooner they can suggest ways to help you deal with them.

Find out more about radiation therapy and side effects of radiation therapy. To make the decisions that are right for you, ask your healthcare team questions about radiation therapy.