Efficacy of Repeat Stereotactic Radiation in Patients With Intraprostatic Tumor Recurrence

Overview

Stereo-Re-Pro aims to provide further evidence of Stereotactic Body Radiotherapy (SBRT) as a supplementary non-invasive curative treatment for local recurrence following radiotherapy. The objective of the first part of the trial (Phase I) is to select the recommended dose for salvage SBRT (either 5 x 6 Gy, 6 x 6 Gy, or 5 x 5 Gy) based on dose-limiting toxicity observed during the 18 weeks following the initiation of salvage-SBRT. Particular attention will be paid to the quality of life and tolerance of the treatment. The objective of the second part of the trial (phase II) is to estimate the efficacy of the salvage-SBRT in terms of biochemical relapse-free survival rate.

To date, no standard local treatment exists for patients with an intraprostatic recurrence after radiotherapy. A number of treatments options exist including: radical prostatectomy, brachytherapy, High-intensity focused ultrasound (HIFU), cryotherapy, and stereotactic radiotherapy. These treatments are associated with a variety of genitourinary and gastrointestinal toxicities and complications. In recent years, stereotactic radiotherapy has been used to treat localized prostate cancer in the primary setting but also as a salvage treatment after failure of radiotherapy. The initial results of these studies are promising, with respect to survival and tolerance, but further studies are required to confirm these initial results. The objective of STEREO-RE-PRO is to prospectively evaluate salvage SBRT for intraprostatic recurrent prostate cancer after primary external radiotherapy. This study will select patients for whom there is no standard local treatment. After inclusion and non-inclusion criteria have been verified and the patient has consented, the site will register the screening and organize the baseline visit with the placement of fiducial markers within two months before the planned start of SBRT. Once the fiducial placement has been performed and all eligibility criteria fully reviewed, the site will register the patient's participation so that the bio-statistician allocates the dose of SBRT. The dose will be allocated upon a model-based estimates provided by the statistical team and confirmed by the trial steering committee. Five or six fractions, at a level of 5 or 6 Gy per session (either 5 x 6 Gy, 6 x 6 Gy, or 5 x 5 Gy), will be delivered over a maximum of 12 days to provide a total dose of 25 to 36 Gy. During the treatment phase of the study, no study specific visits are scheduled and the patients will be followed as per standard of care. A follow-up visit is planned at 6, 10, 18 weeks from the start of SBRT for safety evaluation. Subsequent follow-up visits are planned at 6, 9, 12, 18, 24, 30, and 36 months after the start of radiotherapy. Thereafter, yearly follow-up visits at 48, 60, and 72 months after starting SBRT will be planned after the initial 3-year follow-up period. M72 visit corresponds to the end of study visit.