Rationale of Technical Requirements for NRG-BR001: The First NCI-Sponsored Trial of SBRT for the Treatment of Multiple Metastases

Publication date: Available online 20 May 2016
Source:Practical Radiation Oncology
Author(s): Hania A. Al-Hallaq, Steven Chmura, Joseph K. Salama, Kathryn A. Winter, Clifford G. Robinson, Thomas M. Pisansky, Virginia Borges, Jessica L. Lowenstein, Susan McNulty, James M. Galvin, David S. Followill, Robert D. Timmerman, Julia R. White, Ying Xiao, Martha M. Matuszak
IntroductionIn 2014, the NRG Oncology Group initiated the first NCI-sponsored, phase I clinical trial of SBRT for the treatment of multiple metastases in multiple organ sites (XXXX; NCTXXX). The primary endpoint is to test the safety of SBRT for the treatment of multiple lesions (2-4) in several anatomic sites in a multi-institutional setting. Because of the technical challenges inherent to treating multiple lesions as their spatial separation decreases, we present the technical requirements for NRG-XXXX and the rationale for their selection.Methods and MaterialsPatients with controlled primary tumors of breast, non-small cell lung, or prostate are eligible if they have 2-4 metastases distributed among 7 extracranial anatomic locations throughout the body. Prescription and organ-at-risk (OAR) doses were determined by expert consensus. Credentialing requirements include 1) irradiation of the IROC phantom with SBRT, 2) submitting IGRT case studies, and 3) planning the benchmark. Guidelines for navigating challenging planning cases including assessing composite dose are discussed.ResultsDosimetric planning to multiple lesions receiving differing doses (45-50Gy) and fractionation (3-5) while irradiating the same organs-at-risk is discussed, particularly for metastases in close proximity (≤5cm). The benchmark case was selected to demonstrate the planning trade-offs required to satisfy protocol requirements for two nearby lesions. Examples of passing benchmark plans exhibited a large variability in plan conformity.DiscussionNRG-XXXX was developed using expert consensus on multiple issues from the dose fractionation regimen to the minimum IGRT guidelines. Credentialing was tied to the task rather than the anatomic site in order to reduce its burden. Every effort was made to include a variety of delivery methods to reflect current SBRT technology. While some simplifications were adopted, the successful completion of this trial will inform future designs of both national and institutional would allow immediate clinical adoption of SBRT trials for oligometastases.



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