Toxicity and Local Control Outcomes for Brain Metastases Managed with Resection and Aggressive Reirradiation after Initial Radiosurgery Failure

Abstract Objectives To describe toxicity and tumor outcome after resection and aggressive re-irradiation (stereotactic radiosurgery(SRS) or brachytherapy) of brain metastasis that have pathologically confirmed recurrence after prior radiosurgery. Methods A retrospective chart review identified 40 lesions in 35 patients that were initially treated with SRS, then demonstrated evidence of recurrence with pathologic confirmation and underwent re-irradiation either with radiosurgery (n=28, 70%) or intracavitary brachytherapy with Cesium-131 seeds (n=12, 30%). Toxicity was measured by: steroids initiated or increased within 3 months, imaging evidence of treatment effect vs disease progression at any time point, further intervention for local recurrence or necrosis, and any grade 3/4 neurologic events. Local control (with failure defined by sustained progression on imaging or pathologic confirmation of tumor) was measured from time of retreatment. Results Median follow-up from time of re-irradiation was 11.8 months (range 1 – 89.7 months). Dose for repeat radiosurgery was 18–25 Gy in 1–5 fractions, and brachytherapy dose was 55–65 Gy at 5 mm depth. Twelve lesions subsequently had imaging evidence of radionecrosis vs. progression. Of these, eight underwent repeat resection with pathology demonstrating radiation necrosis in five patients (n=4 with SRS, n=1 with brachy) and tumor recurrence in 3 (n=2 with brachy, and n=1 with SRS). Toxicities included: Steroids, 14(35%); imaging progression/necrosis 12(30%); grade 3/4 event, 3(20%); and surgically confirmed radionecrosis 5(12.5%). Local control of retreated lesions at 6 months is 85.5%, and at 12 months is 79.3%, OS at 1 year is 52.5% and at 2 years 46.6%. Local control at one year for repeat stereotactic treatment was 82.9% and for Cs131 brachytherapy was 80.8% Conclusions Aggressive re-irradiation after resection for pathologic confirmation appears to be appropriately safe and effective for the majority of patients after local failure of initial radiosurgery.