Radiation Therapy for Pancreatic Neuroendocrine Tumors (pNET)

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

Although surgery is the main treatment for most pancreatic neuroendocrine tumors (pNETs),  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 for pNETs

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. This 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.

These side effects usually disappear within a few weeks of the treatment. Ask your doctor what side effects to expect and how to prevent or relieve them.

Radioactive drug therapies for pNETs

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, now 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.

Side effects of 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 about yttrium-90 and 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.