With the exception of skin cancer, prostate cancer is the most commonly diagnosed cancer and the third highest cause of cancer-related mortality in men. It is estimated that 23,600 new cases of prostate cancer were diagnosed in Canada in 2014, resulting in a lifetime probability of developing prostate cancer of 14.1%. Approximately 4,000 Canadian men died of prostate cancer in 2014 (approximately one in six diagnosed). A team of investigators at the Robarts Research Institute in London, in collaboration with investigators at the Princess Margaret Hospital, have invented a new system for treatment of prostate cancer. The new system addresses the important realization that low- and intermediate-risk prostate cancers are being overtreated by whole gland therapies such as radical surgery (removing the complete prostate) or radiation therapy. There is general agreement now that properly executed selective focal ablative therapy on rigorously selected patients could provide an important option for definitive management with minimal treatment-related adverse side effects on urinary and sexual function (associated with radical surgery), and bowel function (associated with external-beam radiation therapy). The new system will allow accurate, precise and efficient focal therapy of the prostate. The system uses a laser thermal therapy approach with the patient inside the bore of an MRI scanner, and provides accurate imaging of the cancer, guidance of the laser fiber into the tumour and thermal mapping for controlling the ablation zone. The system will be built and then tested with 10 patients at the London Health Sciences Centre and the University of Chicago.