Abstract
PurposeStereotactic radiosurgery (SRS) is an established primary treatment for newly diagnosed brain metastases with high local control rates. However, data about local re-irradiation in case of local failure after SRS (re-SRS) are rare. We evaluated the feasibility, efficacy and patient selection characteristics in treating locally recurrent metastases with a second course of SRS.MethodsWe retrospectively evaluated patients with brain metastases treated with re-SRS for local tumor progression between 2011 and 2017. Patient and treatment characteristics as well as rates of tumor control, survival and toxicity were analyzed.ResultsOverall, 32 locally recurrent brain metastases in 31 patients were irradiated with re-SRS. Median age at re-SRS was 64.9 years. The primary histology was breast cancer and non-small-cellular lung cancer (NSCLC) in respectively 10 cases (31.3%), in 5 cases malignant melanoma (15.6%). In the first SRS-course 19 metastases (59.4%) and in the re-SRS-course 29 metastases (90.6%) were treated with CyberKnife® and the others with Gamma Knife. Median planning target volume (PTV) for re-SRS was 2.5 cm3 (range, 0.1–37.5 cm3) and median dose prescribed to the PTV was 19 Gy (range, 12–28 Gy) in 1–5 fractions to the median 69% isodose (range, 53–80%). The 1-year overall survival rate was 61.7% and the 1-year local control rate was 79.5%. The overall rate of radiological radio-necrosis was 16.1% and four patients (12.9%) experienced grade ≥ 3 toxicities.ConclusionsA second course of SRS for locally recurrent brain metastases after prior local SRS appears to be feasible with acceptable toxicity and can be considered as salvage treatment option for selected patients with high performance status. Furthermore, this is the first study utilizing robotic radiosurgery for this indication, as an additional option for frameless fractionated treatment.
Highlights
Brain metastases are diagnosed in up to 40% of patients with solid primary tumors outside the central nervous system and the incidence is continuously increasing [1]
32 locally recurrent brain metastases in 31 patients were irradiated with re-Stereotactic radiosurgery (SRS)
Median planning target volume (PTV) for re-SRS was 2.5 cm3 and median dose prescribed to the PTV was 19 Gy in 1–5 fractions to the median 69% isodose
Summary
Brain metastases are diagnosed in up to 40% of patients with solid primary tumors outside the central nervous system and the incidence is continuously increasing [1]. Novel systemic agents like targeted therapies and immune check point inhibitors have recently improved survival of metastatic patients [11,12,13,14,15], so that the relative rare event of a local recurrence of a metastasis previously treated with SRS could become increasingly important. In such cases surgery [16, 17] or whole-brain radiotherapy (WBRT) [18, 19] are currently the most common treatment practices, both of these treatment modalities present some problems. WBRT leads to a relative quick and frequent decline in cognitive function [4, 21] and it would be desirable to avoid or defer this treatment if not absolutely necessary, especially for this often extracranially controlled patient subgroup with a limited number of metastases
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