Radiation therapy for neuroendocrine cancer

Radiation therapy uses high-energy rays or particles to destroy cancer cells.

Radiation therapy is sometimes used to treat neuroendocrine cancer. Your healthcare team will use what they know about the cancer and about your health to plan the type and amount of radiation, and when and how it is given.

Most people who have radiation therapy for neuroendocrine cancer have had other treatments first. You may have radiation therapy to:

• treat a neuroendocrine tumour (NET) that has spread (metastasized)
• treat a NET when surgery can’t be done
• treat a neuroendocrine carcinoma (NEC)
• destroy cancer cells left behind after surgery or liver-directed therapy to reduce the risk that the cancer will come back (recur) (called adjuvant therapy)
• relieve symptoms caused by neuroendocrine cancer (called palliative therapy)

Radiation therapy and chemotherapy may be given during the same time period to treat neuroendocrine cancer. This is called chemoradiation. Some chemotherapy drugs can help make radiation work better by making cancer cells more sensitive to radiation. Combining chemotherapy and radiation therapy can be more effective than either treatment on its own.

The following types of radiation therapy are most commonly used to treat neuroendocrine cancer.

Internal radiation therapy places radioactive materials in the body. Larger doses of radiation can be given with internal radiation therapy than with external radiation therapy.

When treating NETs, the radioactive material is usually combined with a drug to form 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.

Peptide receptor radionuclide therapy (PRRT) combines a radioactive material, usually lutetium-177 (Lu-177), with a type of hormone drug called a somatostatin analogue that binds to receptors on tumours. This creates a radiopharmaceutical that can travel through the blood to reach cells all over the body (systemic radiation). Cancer cells take up the radioactive material, and this material destroys the cancer cells.

For PRRT to work, the cancer cells must have receptors for somatostatin to target and then attach to. NETs that have cells with these receptors are described as somatostatin-receptor positive. Most people need a PET scan before being considered for PRRT. The scan shows if somatostatin attaches to NET cells.

Lutetium-177 octreotate (Lutathera) is a PRRT used to treat gastrointestinal and pancreatic NETs when:

• surgery can’t be done because of the size of the tumour or where it is
• the cancer has continued to grow (progressive) and spread (metastasized)

Radiolabelled MIBG combines a radioactive iodine with a substance that is absorbed by neuroendocrine cells called metaiodobenzylguanidine (MIBG). The radioactive material travels through the blood to reach cancer cells all over the body. It enters the cells through a special channel in the cell wall and then destroys them.

Radiolabelled MIBG may be used to treat some types of NETs. Most people need an MIBG scan before being offered this treatment.

During external radiation therapy, a machine directs radiation through the skin to the tumour and some of the tissue around it. External radiation therapy is also called external beam radiation therapy.

External radiation therapy is sometimes used to treat some types of NETs and NECs. It may also be given to relieve pain and manage symptoms from bone metastases or brain metastases.

Find out more about bone metastases and brain metastases.

During radiation therapy, your healthcare team protects healthy cells in the treatment area as much as possible. Side effects of radiation therapy will depend mainly on the size of the area being treated, the specific area or organs being treated, the total dose of radiation, the type of radiation used and the treatment schedule. Tell your healthcare team if you have side effects that you think are from radiation therapy. The sooner you tell them of any problems, the sooner they can suggest ways to help you deal with them.

These are common side effects of radiation therapy for neuroendocrine cancer:

• nausea and vomiting
• low blood cell counts
• fatigue
• skin problems, including redness and irritation, most often from external beam radiation therapy
• high blood pressure
• low platelet counts
• kidney inflammation
• pain

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.