MRI Targeted Focal Laser Thermal Therapy of Biopsy Confirmed Prostate Cancer

This is a single center, single arm, open-label Phase I study to establish the safety of interstitial laser thermal therapy (ILTT) in patients with a single site of low grade (Gleason \<7) prostate cancer who have not yet received treatment for their cancer. No control group will be utilized and all patients will receive laser thermal therapy. The patient will undergo multimode MRI to determine if a single site of prostate cancer can be localized by this technique and to localize the tumor in 3 dimensions within the prostate. A multicore (12 + cores) mapping transrectal ultrasound guided biopsy of the prostate would then confirm that no other sites of cancer exist. Each patient will complete quality of life and performance questionnaires. ILLT will be performed under general anesthetic in a procedure similar to brachytherapy, using transrectal ultrasound to guide insertion of the laser and monitoring probes into the sector containing the cancer as visualized by the MR scan. Following the procedure, patients will be assessed for clinical signs of urinary, rectal, and erectile complications and will complete validated self-assessment tools on these functions. MRI at 7 days and MRI and biopsy at 6 months will be used to assess the extent of tissue effect and presence of cancer due to ILTT. Patients will remain on standard Watchful Waiting surveillance for any further sign of disease progression. ILLT will not restrict any future treatment of prostate cancer. To minimize the treatment risk, participants in the trial will be staged according to location of the disease in the prostate. The first 3 participants recruited to the trial will have targeted loci well separated from the urethra, erectile nerves and the rectum, and so treatment in this region poses minimal risk of injury to these vital structures. Lesions sizes measured in this initial stage will be used in planning fiber placement in the three remaining stages, in which fiber placement is closer to critical structures such as the urethra (Stage 2), erectile nerves (Stage 3) and rectum (Stage 4).