Abstract 737: Hypofractionated stereotactic radiotherapy to surgical cavity after resection for brain metastasis

Abstract

Abstract Recurrence at resection cavity after resection for brain metastasis is high; whole brain radiotherapy (WBRT) decreases this risk but may cause neurocognitive complication. Post-operative radiosurgery to resection cavity is a new technique to decrease recurrence and spare patients from WBRT, but single high-dose fraction may potentially increase radiation-induced necrosis. Hypofractionated stereotactic radiotherapy (SRT) delivers higher radiobiological dose which may potentially provide higher local tumor control, and fractionation may lower risk of radiation-induced injury. To investigate the efficacy of post-operative hypofractionated SRT after resection of brain metastasis, we retrospectively analyzed 52 consecutive patients with brain metastasis from solid tumors who underwent surgical resection followed by SRT to the resection cavity for at least one metastasis from April 2008 to March 2011. A total of 25 to 30 Gy in 5 daily fractions over 1-week period was prescribed to the resection cavity with a margin of 2 mm expansion (median dose 28.5 Gy) between 2 to 4 weeks post-operatively. Synchronous oligometastasis, if present, was treated with radiosurgery. No patients received upfront WBRT. All patients were followed up for at least 6 months. Follow-up was assessed using clinical evaluation and MR imaging every 2 to 3 months. The radiographic end point was local tumor control at resection cavity. Preliminary analyses showed the actuarial local control rate of 86% at 12 months at the resection site. For those with synchronous brain metastasis, the rates of local control at resection cavity and oligometastases were not statistically significantly different (p=0.4). Approximately 30% of the patients developed distant brain recurrence during follow-up, and 70% of these patients received salvage radiosurgery while the rest received WBRT. None of the patient developed radiation-induced injury at the resection site. Multivariate analysis showed that number of metastasis was associated with higher rate of distant brain recurrence. Hypofractionated SRT appears to be safe and effective in preventing recurrence at resection cavity following surgical resection of brain metastasis and may spare many patients from WBRT and its adverse effects. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 737. doi:1538-7445.AM2012-737