MR Image Guided Therapy in Prostate Cancer

Background: \- One way to treat prostate cancer is to use a laser to direct extreme heat to a small area of the prostate. The heat destroys tumor cells but does not affect healthy tissue. Doctors want to see if magnetic resonance imaging (MRI) can be used to improve this treatment. MRI will be used to help locate tumor cells and guide the laser during surgery. However, MRI-guided laser therapy has not been used to treat many people with prostate cancer. More studies are needed to see whether it can destroy tumor cells permanently. Objectives: \- To test the safety and effectiveness of treating prostate tumors with laser therapy guided by magnetic resonance imaging. Eligibility: \- Men at least 18 years of age who have prostate cancer that can be seen with an MRI and has not spread to other parts of the body. Design: * Participants will be screened with a physical exam and medical history. They will also have blood tests and imaging studies, and will complete questionnaires about their health. * Participants will have the MRI-guided laser treatment in the hospital. The doctor will use the MRI to control how much energy is delivered by the laser and how much tissue is destroyed. The entire procedure usually takes from 1.5 to 3 hours. * After the treatment, participants will have a catheter put in to keep the bladder emptied. The catheter will stay in for 1 to 7 days. Drugs to prevent infection and bladder spasms will be given. Participants will leave the hospital once they are well enough to go home. * Participants will have follow-up visits 3, 6, 9, 12, 18, 24, and 36 months after the therapy. They will have physical exams, and blood and urine tests. They will also answer questionnaires. Participants will have MRI scans 6, 12, 24, and 36 months after the therapy. They will have a prostate biopsy to see if there is any tumor every 12 months for the first 2 years. Another biopsy may be done in the third year.