Radiation therapy for gastrointestinal carcinoid tumors
External beam radiation therapy (EBRT)
In this form of radiation therapy, a machine aims a beam of high-energy rays (or particles) to kill cancer cells. It is like having a regular x-ray except it takes longer and uses much higher amounts of radiation. Patients typically have treatments 5 days a week for several weeks.
This is the type of radiation used most often to treat cancer. Unfortunately, EBRT is not very effective against most gastrointestinal (GI) carcinoid tumors. It is used mainly to treat pain from cancers that have spread to the bones or other parts of the body. Although surgery is the first option for most carcinoid tumors, those who can't have surgery might choose radiation therapy.
The main side effects of GI radiation therapy are:
- Tiredness (fatigue)
- Nausea and vomiting
- Diarrhea (if the belly or pelvis is treated)
- Skin changes, which can range from mild redness to blistering and peeling
- Hair loss in the area being treated
This technique combines embolization with radiation therapy and is used to treat liver metastases. Embolization reduces blood flow to a tumor by injecting materials that plug up the artery feeding the area of the liver containing the tumor. This artery that is blocked is a branch of the hepatic artery, the artery that feeds the liver. Most of the healthy liver cells will not be affected because they get their blood supply from another blood vessel (the portal vein).
In this procedure a catheter is put into an artery in the inner thigh and threaded up into the liver. A dye is usually injected into the bloodstream at the same time to allow the doctor to monitor the path of the catheter via angiography, a special type of x-ray. Once the catheter is in place, small particles called microspheres are injected into the artery to plug it up.
In radioembolization, microspheres that are attached to a radioactive element called yttrium-90 (or 90Y) are used (some brand names for these beads include TheraSphere® and SIR-Spheres®). After they are injected, 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 tumor cells. The radiation travels a very short distance, so its effects are limited mainly to the tumor.
In this form of radiation therapy, a drug is linked to a radioactive element. The drug travels throughout the body, attaches to the cancer cells, and gives off radiation to kill them. This type of treatment has been used for a long time to treat some cancers, but is now also being used to treat carcinoid tumors. One option is to use I-131 MIBG in higher doses than are normally used to image carcinoid tumors (see “Imaging tests” in the section “How are gastrointestinal carcinoid tumors diagnosed?” Treatment using I-131 MIBG is available in Europe, but is not available in the United States.
Another being studied is a drug like octreotide called edotreotide linked with a radioactive form of the element yttrium. This is discussed in more detail in “What's new in gastrointestinal carcinoid tumor research and treatment?”
For more information on radiation therapy, see the Radiation Therapy section of our website, or read Understanding Radiation Therapy: A Guide for Patients and Families.
Last Medical Review: 02/26/2015
Last Revised: 02/08/2016