Low Risk Prostate Cancer

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.

This is a multicenter, prospective diagnostic accuracy study evaluating the Istanbul PSMA PET/CT Criteria (IPPC) for selecting patients with biopsy-confirmed low-risk prostate cancer (ISUP Grade 1) for active surveillance (AS). The study integrates delayed Ga-68 PSMA PET/CT imaging into the diagnostic pathway to refine patient stratification, minimize overtreatment and potentially reduce unnecessary biopsies and MRI, or exposing high-risk individuals to the danger of cancer progression if left untreated scans.

This study aims to identify patients with low-risk prostate cancer (ISUP Grade Group 1) eligible for active surveillance who are at higher risk of upgrading to ISUP Grade Group 2 or higher at confirmatory biopsy one year after diagnosis. Patients with low-risk ISUP GG1 tumors will be selected and undergo: * PSMA PET with calculation of SUVmax and PRIMARY-Likert score * Whole Exome Sequencing (WES) analysis on diagnostic prostate biopsies * Immunohistochemistry on diagnostic prostate biopsies * Confirmatory biopsy one year after diagnosis, as recommended by international guidelines This prospective, monocentric, single-arm interventional study will assess the predictive accuracy of a multivariable model integrating next-generation imaging and molecular biomarkers to improve risk stratification in active surveillance patients.