Enhancing Radiation Therapy Plan Quality in a Multi-Site Randomized Clinical Trial with a Benchmark Credentialing Exercise: The VA STARPORT Experience

Abstract

<h3>Purpose/Objective(s)</h3> VA STARPORT is a phase 2/3 trial comparing systemic therapy +/- PET-directed, metastasis directed radiation therapy (RT) for oligo recurrent prostate cancer enrolling at 16 sites. RT options include SBRT to metastases only or elective nodal RT with a simultaneous integrated boost (ENRT+SIB). We hypothesized that benchmark credentialing exercise results that were shared across study sites would enhance protocol understanding, increase compliance, and identify opportunities to improve the study protocol. <h3>Materials/Methods</h3> A hypothetical benchmark patient scenario was created including prior definitive prostate RT with recurrences in a right obturator node, right external iliac node, and right iliac bone. OARs, target structures, and prior RT dosimetry were created on an open-source CT dataset. The benchmark exercise included: Phase 1: Each site described their preferred protocol treatment approach (SBRT or ENRT+SIB) and RT details (dose, fractions, PTV margins, and method to address prior RT). Phase 2: Each site performed 2 standardized treatment planning exercises on the dataset (SBRT vs. ENRT+SIB). Compliance worksheets summarized and assessed dose metrics, target coverage, and conformality. Plan DICOM files, worksheets, and IMRT QA were submitted for central RT quality assurance (RTQA). Phase 3: SBRT and ENRT + SIB plans were scored by the study RTQA team using a numerical plan scoring system. Scorecards and lessons learned were discussed with local investigators and further communicated to all study sites. <h3>Results</h3> Site survey results (n=16) revealed 8 preferred ENRT+SIB. Only 4 ENRT+SIB prescriptions were per-protocol, and there was PTV margin non-compliance in an intended SBRT plan. Benchmark lessons learned are summarized in the Table. <h3>Conclusion</h3> A practical and useful benchmark exercise successfully assessed protocol compliance, revealed key lessons, and identified ways to improve the protocol's RT section and RTQA process. Teaching points and learned planning strategies were shared across study sites and have a potential to improve metastasis-directed RT planning for both trial and non-trial patients at each facility.