The phase I NRG Oncology clinical trial BR001 tested the hypothesis that stereotactic body radiotherapy (SBRT) could be used safely in patients with oligometastatic disease characterized by multiple metastases. Results from the trial indicate that using SBRT is safe as treatment for patients with 2 metastases in close proximity or 3 to 4 metastases regardless of proximity, in the following anatomic locations: peripheral lung, central lung, abdomen/pelvic, bone/osseous, spinal/paraspinal, cervical, and liver. These findings were presented by Chmura et al at the 2018 American Society for Radiation Oncology (ASTRO) Annual Meeting and published in the International Journal of Radiation Oncology • Biology • Physics.
The study accrued 36 patients between August 2014 and December 2017, 12 of whom had breast cancer; 11, non–small cell lung cancer; and 13, prostate cancer. All patients in this study were followed for dose-limiting toxicity defined by any grade 3 through 5 adverse events that occurred either definitely or probably from SBRT within 6 months of receiving the treatment. These patients were categorized into those with metastases in seven different anatomic locations: bone/osseous, spinal/paraspinal, peripheral lung, central lung, abdominal/pelvic, mediastinal/cervical, and liver.
No prespecified dose-limiting toxicities were reported for bone/osseous, spinal/paraspinal, peripheral lung, central lung, and/or abdominal/pelvic locations. At the time of data lock for this analysis, the dose-limiting toxicity follow-up periods for mediastinal/cervical and liver metastases were ongoing.
“While the SBRT dose schedule used in this trial is typical when treating single metastases, the patients who participated in NRG-BR001 had a median of three metastases and displayed zero protocol-defined dose-limiting toxicities across the evaluable anatomic locations. We attribute this safety to the rigorous quality assurance and advanced imaging used by all participating centers, which had to be credentialed before they were allowed to treat any patients who volunteered to participate on this trial,” stated first study author Steven J. Chmura, MD, PhD, Associate Professor of Radiation and Cellular Oncology at the University of Chicago Medicine.
Based on the results of this trial, NRG-BR001, the ongoing, randomized NRG Oncology trial NRG-BR002, a breast cancer–specific trial, has been expanded to allow up to 4 metastases. These results may also be able to be incorporated into other trials, such as immunotherapy trials using SBRT to target multiple metastases.
The trial was supported by National Cancer Institute grants U10CA180868, U10CA180822, and UG1CA189867.
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