Magnetic Resonance-Guided High-Dose Brachytherapy (Short-Range Radiation Therapy) for Prostate Cancer

Overview

This study will evaluate the use of magnetic resonance imaging (MRI) for guiding placement of hollow needles into the prostate gland for delivering internal radiation therapy to patients with prostate cancer. Prostate cancer is often treated with a combination of external beam radiation therapy and brachytherapy (internal radiation delivered close to the tumor). This study will determine whether MRI is more accurate in guiding needle placement than ultrasound, which is currently used for this purpose. Patients will have one brachytherapy treatment followed by 5 weeks of external beam treatments and a second brachytherapy. Patients 18 years of age and older with prostate cancer that has not spread to the bone may be eligible for this study. Candidates will be screened with a physical examination, blood and urine tests, and a bone scan. To plan for radiation therapy, patients will have standard computed tomography (CT) and MRI scans of the pelvis and prostate. In addition, CT and MRI scans will be done to determine if the prostate is in a good position for brachytherapy. For these scans, patients will have an enema and a tube will be placed in the rectum. They will then lie still on their side for about 45 minutes during the scan. Patients who have blood in their urine will also undergo cystoscopy. This is an examination of the bladder using a small camera that is advanced through the penis into the bladder. Patients are given an antibiotic for 2 days before the brachytherapy and on the morning of the procedure. Before the test, they have a small enema and are given medicines through the vein and into the spine for relaxation and to decrease any discomfort. (The test is done under general anesthesia for patients who require it.) The patient is moved on a stretcher into the MRI scanner and a catheter is inserted into the bladder through the penis. The bladder is filled with water and a tube is placed in the rectum. With the help of a plastic guide placed against the skin, about 14 to 18 needles are then placed in the prostate. Some stitches are sewn to hold the needles and the guide in place, and the tube in the rectum is removed. The patient is the transferred from the MR scanner into the CT scanner, where the rectal tube is reinserted and the needles are adjusted. A cystoscopy is done to make sure the needles do not enter the bladder. When the needles are adjusted, the tube is removed from the rectum and the patient is moved to the radiation oncology clinic. After a few hours, when the radiation dose has been calculated, a radioactive substance called iridium is administered. The needles placed in the prostate are connected to a radiation machine, and thin wires with radioactive material on the tips are inserted into each needle and withdrawn a little at a time. The process takes about 20 to 30 minutes. The patient is then disconnected from the machine and undergoes another MRI scan to confirm the position of the needles. The needles and catheter are then removed and the patient is monitored for a while before going home. Patients then have 5 weeks of external beam therapy, followed by a second brachytherapy treatment. Patients return to the clinic at 1, 3, 6, 12, 18, 24, 36, 48, and 60 months after treatment for blood tests, physical examination, and review of symptoms.