Adjuvant therapy after resection of brain metastases

Abstract

Tumor bed stereotactic radiosurgery (SRS) after resection of brain metastases is a new strategy to delay or avoid whole-brain irradiation (WBRT) and its associated toxicities. This retrospective study analyzes results of frameless image-guided linear accelerator (LINAC)-based SRS and stereotactic hypofractionated radiotherapy (SHRT) as adjuvant treatment without WBRT. Between March 2009 and February 2012, 44resection cavities in 42patients were treated with SRS (23cavities) or SHRT (21cavities). All treatments were delivered using a stereotactic LINAC. All cavities were expanded by ≥ 2mm in all directions to create the clinical target volume (CTV). The median planning target volume (PTV) for SRS was 11.1cm(3). The median dose prescribed to the PTV margin for SRS was 17Gy. Median PTV for SHRT was 22.3cm(3). The fractionation schemes applied were: 4fractions of 6Gy (5patients), 6fractions of 4Gy (6patients) and 10fractions of 4Gy (10patients). Median follow-up was 9.6months. Local control (LC) rates after 6and 12months were 91and 77 %, respectively. No statistically significant differences in LC rates between SRS and SHRT treatments were observed. Distant brain control (DBC) rates at 6and 12months were 61and 33 %, respectively. Overall survival (OS) at 6and 12months was 87and 63.5 %, respectively, with a median OS of 15.9months. One patient treated by SRS showed symptoms of radionecrosis, which was confirmed histologically. Frameless image-guided LINAC-based adjuvant SRS and SHRT are effective and well tolerated local treatment strategies after resection of brain metastases in patients with oligometastatic disease.