High-Dose-Rate Brachytherapy

Official Title

MRI-Guided HDR Brachytherapy for Prostate Cancer

Summary:

This pilot study initiates a research program testing the early technical and clinical performance of a novel procedure for MRI-guided high-dose-rate (HDR) prostate brachytherapy. Testing will proceed in two cohorts of patients. In Arm 1, patients with locally recurrent prostate cancer after radiation therapy will receive tumour-targeted salvage HDR brachytherapy. Arm 1 of the study will be coordinated and closely integrated with a separate concurrent study of MRI-guided prostate biopsy, which will be performed prior to accrual to Arm 1 of this trial (UHN 05-0641-C). In arm 2, patients with locally advanced prostate cancer will receive a boost of prostate-targeted HDR brachytherapy during external beam radiation therapy. This technique will be prospectively evaluated in up to 100 patients. Preliminary data acquired in this pilot study will determine the technical limits of MRI guided HDR brachytherapy and will be critical for the judicious conduct of a subsequent phase II clinical trial. This proposal is innovative in two fundamental ways: MRI-guidance, and specific tumour targeting for HDR brachytherapy. Successful completion of this study will further individualize local therapy, not only for the benefit of the proportion of cancer patients for whom initial radiotherapeutic interventions have failed, but also provide valuable technical and clinical validation that these novel image-guided (IG) approaches are clinically feasible and could be applied more broadly in prostate cancer therapy.

Trial Description

Primary Outcome:

• To determine if MRI-guided HDR brachytherapy is associated with favourable measures of technical performance.

Secondary Outcome:

• determine if prostate targeted & MRI-guided HDR BT is associated with favourable preliminary measures of clinical performance as boost to EBRT;if tumour-targeted & MRI-guided HDR BT is associated with favourable preliminary measures of clinical performance
• determine dose-response relationships for salvage brachytherapy with a 20% escalation in dose.

Two hundred and nineteen thousand new cases of prostate cancer have been projected in the Unites States for 2007, with external beam radiation therapy (EBRT) constituting the mainstay of local therapy for an increasing proportion of newly diagnosed patients. Despite improvements in the delivery and reduction in associated toxicity of external beam radiation therapy, local persistence or recurrence of disease remains prevalent in 25-51% of patients. Local disease after EBRT is a risk factor for subsequent metastatic progression and prostate cancer-specific mortality, and is a cause of morbidity including hematuria, obstructive uropathy, and chronic pain. Given its prevalence, and the lack of satisfactory local salvage treatments, fear of prostate cancer recurrence has been shown to impose a substantial burden of suffering in patients. Stereotactic needle placement under MRI-guidance enables two critical steps in tumour-targeted brachytherapy: 1) directly guiding brachytherapy catheters to sites of tumour recurrence, and 2) permitting treatment planning and delivery to be based on 3D MRI images. MRI-based HDR brachytherapy will precisely identify the location of brachytherapy catheters relative to the target volumes and adjacent normal structures at risk of radiation injury, obviating the need for invasive saturation (24-100) mapping biopsies. This study will build the evidence supporting the concept of MRI-guidance and tumour-targeted HDR brachytherapy in the management of prostate cancer. This trial will strive to demonstrate improvements in technical performance under MRI-guidance, while exploring a novel paradigm of patient-specific modulation of dose intensity based on regions of tumour burden.

View this trial on ClinicalTrials.gov