High Dose Rate (HDR) Brachytherapy Salvage After Prostatectomy

Magnetic Resonance Imaging (MRI)/ Positron Emission Tomography (PET) Prostate-specific Membrane Antigen (PSMA) -Based Phase I-II Study of Salvage HDR Brachytherapy and External Beam Irradiation In Isolated Tumor Bed Relapses After Radical Prostatectomy

The goal of this observational study is to learn about the long-term effects of HDR Brachytherapy in men with isolated local relapses after radical prostatectomy. The main question it aims to answer is:

Does HDR Brachytherapy increase control rates and decreases complications compared with conventional External Irradiation?

Participants will be asked to receive HDR brachytherapy as part of their regular medical care for isolated local relapses after radical prostatectomy

HDR brachytherapy appears to be an ideal technique for dose escalation in PET/MRI+ (positron emission tomography) , small, well-defined IPBR that can be accessed and visualized through the perineal route with transrectal ultrasound (TRUS) guidance. Additionally, HDR brachytherapy can spare from high dose irradiation most of the vesicourethral anastomosis, the external urinary sphincter (EUS) and the penile bulb. This may be crucial in circular structures such as EUS that are particularly sensitive to whole-volume irradiation but tolerate well high small-volume doses provided that the rest of the EUS is spared.

In this study, HDR brachytherapy will be combined with external beam radiation and 6 months of androgen deprivation therapy to decrease the prostate bed volume irradiated at high-doses while increasing the radiation dose in the PET/MRI+ areas.

Inclusion Criteria:

• Patients with increasing PSA after RP and clinical evidence of PET PSMA/Choline+ and MRI+ isolated prostatic bed relapse (IPBR) that is implantable via transperineal route . The IPBR should be visible on TRUS imaging to allow proper implant placement.
• Pathological confirmation is advised in all cases but it is not mandatory .
• Brachytherapy MRI-based dosimetry
• Patient written Informed Consent of the Institutional Review Board-approved protocol that discloses the investigational nature of the treatment as well as the available standard treatment options.

Exclusion Criteria:

• Distant Metastases
• Isolated nodal relapses
• Prior Irradiation to the IPBR area
• Multicentric IPBRs
• Life expectancy of less than 5 years or inability to tolerate and comply with an HDR procedure