Radiation Therapy for Pancreatic Neuroendocrine Tumor

Radiation therapy uses high-energy rays (such as x-rays) or radioactive particles to kill cancer cells.

Surgery is the main treatment for most pancreatic neuroendocrine tumors (NETs), but radiation therapy may be an option for those who can’t have surgery for some reason. It may also be given alone or with chemotherapy to reduce the size of the tumor and improve symptoms (for example, radiation to the bone to improve bone pain)

External beam radiation therapy

External beam radiation therapy uses a machine to deliver a beam of radiation to a specific part of the body. In general, radiation to the abdomen is avoided as it may cause severe side effects.

Before your treatment starts, the radiation team will determine the correct angles for aiming the radiation beams and the proper dose of radiation. The treatment is much like getting an x-ray, but the radiation is stronger. The procedure itself is painless. Each treatment lasts only a few minutes, although the setup time – getting you into place for treatment – usually takes longer. Most often, radiation treatments are given 5 days a week for several weeks, but this can vary based on the reason it’s being given.

Some common side effects of radiation therapy include:

• Skin changes in areas getting radiation, ranging from redness to blistering and peeling
• Nausea and vomiting
• Diarrhea
• Fatigue
• Loss of appetite
• Weight loss
• Low blood counts, which can increase the risk of serious infection.

Usually these side effects go away within a few weeks after the treatment is complete. Ask your doctor what side effects to expect and how to prevent or relieve them.

Radioactive drugs

Radioembolization

Radioembolization (also known as transarterial radioembolization or TARE) combines embolization with radiation therapy and can be used to treat liver metastases. Small beads called microspheres are attached to a radioactive element called yttrium-90 (or 90Y) and then injected into an artery close to the liver. The beads travel in the liver blood vessels until they get stuck in small blood vessels near the tumor. There they give off radioactivity for a short while, killing nearby tumor cells. The radiation travels a very short distance, so its effects are limited mainly to the tumor.

Peptide receptor radionuclide therapy (PRRT)

People with somatostatin receptor (SSTR)-positive neuroendocrine tumors who have been already treated with octreotide or lanreotide may be candidates for PRRT. In PRRT, a radioactive element, called lutetium-177, is linked to a somatostatin analog, called dotatate, and injected into a vein in the arm. This drug, called Lu-177 dotatate, travels throughout the body, attaches to the somatostatin receptor (a protein) on the cancer cell, and gives off radiation to kill it. The radiation is delivered directly to the tumor, so there is less effect on healthy tissue.

If you are already taking octreotide or lanreotide, you will most likely need to stop taking these medicines for a certain time before you can be treated with PRRT.

Common side effects of PRRT include low levels of white blood cells, abnormal liver test results, nausea and vomiting, high levels of blood sugar, and pain.

Serious side effects include low levels of blood cells, development of certain blood or bone marrow cancers, kidney damage, liver damage, abnormal levels of hormones in the body, and infertility. Tell your cancer care team if you are pregnant or might become pregnant, because Lu-177 dotatate can harm the baby. There is not enough information regarding yttrium-90 in pregnant women so you should discuss this with your doctor. 

Since these drugs expose you to radiation, people who might come into contact with you need to follow certain radiation safety practices to limit their exposure. See Systemic Radiation Therapy for more information.