MRI-guided Locoregional SBRT Prostate Program

The implementation of Magnetic Resonance Image Guided Radiotherapy (MRgRT) into a Prostate Cancer Program will allow to reproduce the results obtained with state-of-the-art brachytherapy combined with EBRT with the added advantage of convenience.

Rationale In the radiation setting, MRI provides superior soft tissue contrast compared to standard onboard X-ray imaging improving inter- and intra- observer delineation variation. MRgRT offers the opportunity to adapt the plan at each fraction to the anatomical changes seen. This is especially important in prostate cancer where the prostate is subject to large intra and/or interfractional position changes due to rectal and bladder filling changes.

Primary Objectives A. To achieve a 5-year biochemical relapse-free survival of 85%. B. To decrease urinary grade 3 or greater toxicity below 5% and rectal grade 3 or greater toxicity below 2%.

Secondary Objectives A. Determination of blood and urine biomarkers of treatment response and toxicity .

B. Determination of radiomics biomarkers of treatment response and toxicity . C. Determination of QOL with IPSS and EORTC QLQ-PR25

Inclusion criteria

• Patients with unfavorable intermediate, high and very high risk PCa as per the NCCN stratification criteria .
• Suboptimal candidates for high-dose therapy such as elderly, frail patients or patients with large volume glands (i.e, >60cm3) or extensive TURP in the prior 6-12 months should be considered cautionary indications.
• Patients with low risk of nodal spread may be treated on a MRI-guided local SBRT program.

Exclusion criteria

• No prior radiation therapy to the target areas
• Patient able to undergo a MRI exam