Radiation is a very powerful therapy in all of cancer, but it is used in special ways with NET patients. The most common type, known as external beam radiation where they put you in a machine and shine radiation from the outside into your body, is less helpful in NETs. However, the two that we do use often are the opposite; they put radiation inside your body and irradiate your tumors from the inside-out.
The one more commonly available here in the United States is called Radioembolization and is ONLY used for the liver. It takes small radioactive beads and injects them through a liver artery and puts radiation into your liver. It tends to select for the tumor because the tumors are more dependent on the arterial supply. However, you do get a fair amount of radiation to the normal liver. The liver usually tolerates the treatment pretty well, but it can have complications. It's particularly effective at helping with symptoms, but can have effects on the tumor size. The major problems are damage to the normal liver and pain. This procedure should be performed by someone with a lot of experience because if it is done incorrectly, the radiation can spread to other places and cause damage, like the stomach or the lungs.
The more interesting internal radiation therapy is the Peptide Receptor Radionuclide Therapy (PRRT). It is mostly available in Europe and other places in the world (see my previous Zebra Blog). Basically, this is an octreotide molecule with a radioactive payload. The octreotide carries the radiation into the tumors selectively ANYWHERE in your body and radiates it for weeks and months. It is being tested in clinical trial by a company called Advanced Accelerator Applications and we are hopeful that it can be approved in the United States soon. The major side effect is bone marrow and kidney suppression.
So, it gets complicated choosing the right therapy at the right time. Make sure you see a NET specialist before making these big decisions.
Eric Liu, MD.--NET Specialist
Chief Medical Advisor-Healing NET Foundation
Surgeon-Neuroendocrine Tumors, Rocky Mountain Cancer Centers, Denver, CO (June 1)