Radioimmunotherapy (RIT)

What is Radioimmunotherapy and how is it used?

RIT combines radiation therapy and immunotherapy. Immunotherapy uses man made monoclonal antibodies to recognize specific types of cancer cells and bind to their surface. Monoclonal antibodies mimic the natural antibodies your immune system produces, to attack bacteria and viruses.

RIT pairs a monoclonal antibody with a radioactive material (radiotracer) to create an agent. The doctor injects the agent into your bloodstream. The agent binds to cancer cells and delivers a high dose of radiation directly to the tumor.

RIT treats non-Hodgkin B-cell and other sub-types of lymphoma, prostate cancer, and neuroendocrine tumors. Doctors use it for new patients and for those who do not respond to chemotherapy or treatment with the agent Rituximab®. In prostate cancer, it is used in patients who become resistant to hormone treatment.

Doctors are developing new RIT agents, some of which are in clinical trials. Potential uses for RIT include treatments for melanoma, ovarian cancer, leukemia, high-grade brain glioma , and colorectal cancer.

Who will be involved in this procedure?

Your treatment team may include a radiologist, nuclear medicine physician, an oncologist, a radiation oncologist, medical physicist, a nurse or nurse practitioner, and a medical and/or radiation oncologist.

What equipment is used?

RIT uses an intravenous (IV) catheter. It may also use a gamma camera to capture images before or after treatment. The doctor may use single-photon emission computed tomography (SPECT-CT) imaging. SPECT-CT uses a combined gamma camera and CT scanner that rotates around the body to produce detailed, three-dimensional images. A PET-CT may also be used before or after your treatment. It is an advanced combination of a nuclear medicine imaging system and a CT scan.

A gamma camera detects radiation and takes pictures from different angles. It may be mounted over or below the exam table or on a gantry. One camera may be above, and another camera may be beneath the table, or the camera may consist of a donut-shaped detector where you will lie on a bed that moves slowly through the detector for imaging.

Who operates the equipment?

A radiologist or other doctor with nuclear medicine training will supervise your treatment. A technologist will operate the gamma camera.

Is there any special preparation needed for the procedure?

Tell your doctor about all the medications you take, including herbal supplements. List any allergies, especially to local anesthetic, general anesthesia or to contrast materials. Your doctor may tell you to stop taking aspirin, nonsteroidal anti-inflammatory drugs (NSAIDs) or blood thinners before your procedure. Tell your doctor if you have trouble emptying your bladder or have trouble with bladder control.

Women should always tell their doctor and technologist if they are pregnant or breastfeeding. Doctors generally do not treat pregnant women or children with RIT. See the Radiation Safety page for more information about pregnancy, breastfeeding, and nuclear medicine imaging.

The doctor will check your blood counts. The doctor will also confirm that your disease is not significantly impacting your bone marrow. Patients who have experience with bone marrow transplant or failed stem cell collection should not receive RIT. Your doctor may follow your blood counts after the procedure for some time to make sure your counts are normal.

A radiation safety specialist will discuss radiation safety precautions with you.

How is the procedure performed?

Your doctor will usually treat you as an outpatient. This will require several separate visits.

Before your radioimmunotherapy, you may receive an IV dose of the antibody (without radioactive material) or an infusion of amino acids, depending on what type of cancer is being treated. The antibody attaches to non-malignant B cells in your body and the amino acid infusion protects your kidneys from the radiation that RIT uses. The IV infusions may take up to two hours. The radioimmunotherapy will be given via intravenous infusion. You will be asked to use the bathroom before and after the procedure. Depending on the type of cancer being treated, the therapy may last anywhere from 2 hours to 6 hours. Your doctor will explain the procedure to you with more detailed information specific to your cancer.

What will I feel during this procedure?

Except for intravenous injections, RIT is relatively painless. Reports of significant discomfort or side effects are rare. You will feel a slight pin prick when the technologist inserts the needle into your vein for the intravenous line. You may feel a cold sensation moving up your arm when they inject the radiotracer. Generally, there are no other side effects.

Are there side effects from the procedure?

There is a small risk of bone marrow damage. Lower blood counts are the most serious side effect. This may occur as late as several months after treatment. It is important to follow up with your doctor regularly because it may lead to bleeding or infection. Frequent blood draws will help monitor your blood counts.

Other side effects may include allergic reaction, fever, chills, low blood pressure, diarrhea, and rash. These possible side effects are usually short-term.

Hypersensitivity reactions from the monoclonal antibodies are rare. However, the risk of reaction increases with the number of treatments. Typically, your doctor will pretreat you with acetaminophen (Tylenol®) or diphenhydramine (Benadryl®).