The PRECISION Study: 3 Fractions of Prostate SBRT and RayPilot HypoCath Image Guidance

The investigators want to investigate whether it is possible to reduce the number of curative radiotherapy doses from 5 to only 3 for men with localized early prostate cancer. The aim of the study is to ensure that the side effects of the 3-dose treatment are the same or potentially lower than those already published when using the 5-dose treatment as used in the UK PACE-B trial (NCT01584258). The name of this type of radiotherapy is Stereotactic Body Radiotherapy (SBRT) or participants may see it referred to as Stereotactic Ablative Radiotherapy (SABR). The study is a two-stage single arm Phase II study open to those Centres that use the RayPilot HypoCath tumour tracking system (Micropos Medical). This commercially available system was not available at the time of the original PACE-B study. The system acts like a Global Positioning Device (GPS) to continuously track the prostate position during radiotherapy. If the prostate moves more than 2mm (about 0.08 in) from its intended position during the treatment, then the radiotherapy team are alerted, and the treatment halted until the prostate moves back into the correct position. The ability to understand exactly where the prostate is throughout the treatment ensures the intended dose hits the cancer and does not accidentally increase the dose to the nearby bladder and rectum. The system is a modification of a standard urinary catheter which sits within the bladder with the GPS placed within the wall of the catheter as it passes through the prostate. The investigators are not testing the system as it is commercially available but using it to improve the accuracy of radiotherapy delivery, reducing the number of days of treatment, minimizing side effects and helping ease the burden on busy radiotherapy Departments.