(P009) Fractionated Stereotactic Radiation in the Management of Previously Irradiated Brain Metastases

Jeffrey Peacock, BS, Kamran Ahmed, MD, Peter Johnstone, MD, Siriporn Sarangkasiri, MS, Arnold Etame, MD, PhD, Michael Yu, MD; University of Central Florida College of Medicine; H. Lee Moffitt Cancer Center

BACKGROUND: Failure of brain metastases to respond following prior radiation therapy (RT) can raise challenges for practitioners. The purpose of this study was to determine outcomes and toxicities associated with reirradiation with fractionated stereotactic radiation therapy (FSRT) of recurrent brain metastases.

METHODS: Thirty-one consecutive lesions in 22 patients were treated with FSRT between January 2010 and December 2014 following prior RT. Patients were treated in five fractions, and doses were prescribed to cover at least 95% of the planning target volume (PTV). The primary endpoint for this study was local failure. Twenty-four lesions (77.4%) received prior whole-brain radiation therapy (WBRT), and seven lesions (22.6%) were treated with stereotactic radiosurgery (SRS) at the site prior to FSRT. The median time between reirradiation with FSRT was 11.5 months (range: 1–97.3 mo).

RESULTS: The 1-year local control rate was 74.3%, and distant control was achieved in six patients (27.3%). The 1-year survival rate was 46.9% and was associated with recursive partitioning analysis (RPA) class designation (P = .044). Four patients (18%)-all of whom received WBRT prior to FSRT-experienced treatment-related side effects; these were managed with steroids, with one lesion found to undergo pathologically confirmed radionecrosis. No toxicities were noted in patients treated with SRS prior to FSRT.

CONCLUSION: In this series, we note good local control with an adequate toxicity profile for brain metastases reirradiated with FSRT.

Proceedings of the 98^th Annual Meeting of the American Radium Society - americanradiumsociety.org