Gastrointestinal Carcinoid Tumors

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Treating Gastrointestinal Carcinoid Tumors TOPICS

Radiation therapy for gastrointestinal carcinoid tumors

External beam radiation therapy

In this form of radiation therapy, a beam of high-energy rays (or particles) is used to kill cancer cells. A machine aims this beam at a specific part of the body. This is the type of radiation used most often for most types of GI cancers. It is like having a regular x-ray except it takes longer and uses much higher amounts of radiation. Patients typically have treatments for 5 days a week for several weeks.

Unfortunately, this type of radiation therapy is not very effective against most 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 cancers, those who can't have surgery might choose radiation therapy.

The main side effects of GI radiation therapy are tiredness (fatigue), nausea, vomiting, diarrhea, and mild, sunburn-like skin changes.

Radioembolization

This technique combines embolization with radiation therapy and is used to treat liver metastases. Embolization reduces blood flow to the cancer cells by blocking the artery feeding the area of the liver containing the tumor. This artery is a branch of the hepatic artery, the artery that feeds the liver. Blood flow is blocked (or reduced) by injecting materials that plug up the artery. 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.

Radiopharmaceuticals

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 radiopharmaceutical being studied is a drug like octreotide called edotreotide labeled with the element yittrium. This is discussed in more detail in the section “What's new in gastrointestinal carcinoid tumor research and treatment?

For more information on radiation therapy, see the “Radiation Therapy” section of our website, our or document Understanding Radiation Therapy: A Guide for Patients and Families.


Last Medical Review: 12/31/2013
Last Revised: 12/31/2013