- What is Radioimmunotherapy and how is it used?
- Who will be involved in this procedure?
- What equipment is used?
- Who operates the equipment?
- Is there any special preparation needed for the procedure?
- How is the procedure performed?
- What will I feel during this procedure?
- Are there temporary or permanent side effects from the procedure?
What is Radioimmunotherapy and how is it used?
Radioimmunotherapy (RIT) is a combination of radiation therapy and immunotherapy. In immunotherapy, a laboratory-produced molecule called a monoclonal antibody is engineered to recognize and bind to the surface of cancer cells. Monoclonal antibodies mimic the antibodies naturally produced by the body’s immune system that attack invading foreign substances, such as bacteria and viruses.
In RIT, a monoclonal antibody is paired with a radioactive material, or radiotracer. When injected into the patient’s bloodstream, the radiation-linked monoclonal antibody, or agent, travels to and binds to cancer cells, allowing a high dose of radiation to be delivered directly to the tumor. The two agents being used today are Yttrium-90 Ibritumomab Tiuxetan (Zevalin®) and Iodine-131 Tositumomab (Bexxar®) for radioimmunotherapy.
RIT is currently used to treat:
- non-Hodgkin B-cell lymphoma (NHL), including both new patients and patients who have not responded to chemotherapy and treatment with the monoclonal antibody Rituximab®.
- other sub-types of lymphoma.
Several new radioimmunotherapy agents are under development or in clinical trials. Potential uses for RIT include the treatment of prostate cancer, melanoma, ovarian cancer, leukemia, high-grade brain glioma and colorectal cancer.
Who will be involved in this procedure?
A radiologist or radiation oncologist who has specialized training in nuclear medicine and other healthcare professionals, such as an oncologist or medical physicist, may be involved in RIT.
What equipment is used?
In addition to equipment needed to start and maintain an IV, images will be obtained with a gamma camera. Often, SPECT imaging will also be performed.
The gamma camera, which is encased in metal, is capable of detecting radiation and taking pictures from different angles. It may be suspended over the examination table or it may be beneath the table. Often, gamma cameras are dual-headed with one camera above and one camera beneath the table. The camera could also be located within a large, doughnut-shaped scanner similar in appearance to a computed tomography (CT) scanner. In some imaging centers, the gamma camera is located beneath the exam table and out of view.
SPECT uses a gamma camera that rotates around the body to produce more detailed, three-dimensional images.
Who operates the equipment?
A radiologist who has specialized training in nuclear medicine will supervise the technologist, who will be directly operating the gamma camera.
Is there any special preparation needed for the procedure?
You should report to your doctor all medications that you are taking, including herbal supplements, and if you have any allergies, especially to local anesthetic medications, general anesthesia or to contrast materials containing iodine (sometimes referred to as "dye" or "x-ray dye"). Your physician may advise you to stop taking aspirin, nonsteroidal anti-inflammatory drugs (NSAIDs) or blood thinners for a specified period of time before your procedure.
Women should always inform their physician or technologist if there is any possibility that they are pregnant or if they are breastfeeding. See the Safety page (www.RadiologyInfo.org/en/safety/) for more information about pregnancy and breastfeeding related to nuclear medicine imaging.
RIT is generally not administered to pregnant women and children.
Pre-screening of patients will occur to ensure proper blood counts and lack of significant bone marrow involvement with disease. Patients who have had prior bone marrow transplantation or failed stem cell collection should not receive RIT.
If you are receiving I-131 Tositumomab (Bexxar®), you will be given supplemental iodine to help protect your thyroid gland prior to and up to two weeks after your therapy. Your physician will instruct you further on which form of iodine you will receive.
You will speak to a radiation safety specialist regarding radiation safety precautions prior to your I-131 Tositumomab (Bexxar®) therapy. Therapies can occur as an outpatient or inpatient depending on your facility and medical condition. If therapy is to be done as an outpatient, your family, home and work situations will be assessed. You will be asked to minimize radiation exposure to others by controlling your distance from others, the time you remain close to them and your personal hygiene. This will usually last between two and seven days. This safety measure is for the protection of those around you. Your physician and medical physicist will discuss the exact length of time of the limitations with you. You may be instructed to take special precautions after urinating, to flush the toilet twice and to wash your hands thoroughly. You should also drink plenty of water to help flush the radioactive material out of your body as instructed by the nuclear medicine personnel.
No special precautions will be needed for Yttrium-90 Ibritumomab Tiuxetan (Zevalin®).
How is the procedure performed?
RIT is usually performed on an outpatient basis and involves several separate visits to the hospital or healthcare facility.
On the first visit, the patient receives a dose of the monoclonal antibody (without radioactive material) via an intravenous (IV) injection. Once in the bloodstream, the monoclonal antibody will attach to non-malignant B cells in the body and protect them from the radiation that will be used in treatment. This IV infusion may take up to two hours. The patient will also receive an intravenous dose of the radiotracer.
During the next week, the patient will return to the hospital or healthcare facility to have a series of images taken to determine where the radiotracer has traveled in the body and how long it remains there. The information obtained from these imaging scans will determine if the patient is a candidate for RIT and will help in planning the treatment. The actual treatment is given in an IV infusion, usually seven to nine days after the first scan.
The actual RIT treatment will be performed one to two weeks later and involves an intravenous injection of the radioactive agent and monoclonal antibody.
What will I feel during this procedure?
Except for intravenous injections, most nuclear medicine procedures are painless and are rarely associated with significant discomfort or side effects.
When the radiotracer is given intravenously, you will feel a slight pin prick when the needle is inserted into your vein for the intravenous line. When the radioactive material is injected into your arm, you may feel a cold sensation moving up your arm, but there are generally no other side effects.
Are there side effects from the procedure?
The most serious side effect of RIT therapy is reducing blood counts. This side effect may occur as late as several months after treatment. As with chemotherapy or radiation therapy, this lowering of blood counts may result in bleeding or infection. It is important to follow up with your treating physician on a regular basis. Frequent blood draws will be performed to monitor your blood count. Less common effects include hypothyroidism (where the thyroid gland does not make enough thyroid hormone) or bone marrow damage.
Additional side effects of RIT, which are usually short-term, may include an allergic reaction, fever, chills, low blood pressure, diarrhea and rash.
Hypersenitivity reactions are rare, with occurrences increasing with multiple therapies. Typically all patients will be pretreated with acetaminophen (Tylenol®) or diphenhydramine (Benadryl®).
Locate an ACR-accredited provider: To locate a medical imaging or radiation oncology provider in your community, you can search the ACR-accredited facilities database.
Exam costs: The costs for specific medical imaging tests and treatments vary widely across geographic regions. Many—but not all—imaging procedures are covered by insurance. Discuss the fees associated with your medical imaging procedure with your doctor and/or the medical facility staff to get a better understanding of the portions covered by insurance and the possible charges that you will incur.
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This page was reviewed on April 30, 2012