PRE-ProstAtectomy MRI-GuidEd Stereotactic Body RadioTherapy for High-Risk Prostate Cancer Trial (PREPARE SBRT)

This is a modified dose escalation and de-escalation study with an expansion of 3 or 6 pts to allow the recommended phase II dose (RP2D) be examined in a total of 9 pts. The dose limiting toxicity (DLT) is defined as Grade 3 or higher toxicity related to preoperative radiotherapy according to the Clavien-Dindo Classification. 3 radiation dose levels, 5 Gy, 6 Gy and 6.5Gy are considered. At the start of each dose level, 3 pts will be enrolled and treated for five days. If none of the 3 pts develop the DLT, the testing dose will escalate to the next level. If 1 of the 3 pts develops the DLT, the current dose will be tested in an additional 3 pts. If no additional pts develop the DLT, the dose will escalate.