Repeat stereotactic radiosurgery for the management of locally recurrent brain metastases.

Stereotactic radiosurgery (SRS) is a well-established treatment option for brain metastases (BM). Repeat SRS for progressive BM is an increasingly used paradigm, although little data is available to support this practice. The goal of this study was to assess the safety and efficacy of a second SRS procedure on a previously treated BM. We performed a retrospective metastasis-level analysis of patients who underwent two SRS procedures on the same lesion and for whom at least 6 months of radiological follow-up was available. The data collected included patient characteristics, clinical symptoms at time of treatment, SRS parameters, radiological response per RANO-BM criteria, clinical evolution and survival. Seventy-five BM in 56 patients were included in the analysis. Most frequent primary histologies were non-small-cell lung cancer (59%) and breast cancer (19%). At the second SRS, median treatment volume was 1.19 cc (range 0.07-20.6) treated with a median margin dose of 18 Gy (range 12-20) at the 50% isodose line (range 30-80%). Median follow-up was 11 months. Progression per RANO-BM criteria occurred in 31%, yielding actuarial local control at 1, 2, and 5 years of 68%, 54% and 54% respectively. At last follow-up, 10 patients (18%) had improved relative to the initial presentation, while 21 (38%) were stable and 25 (44%) were deteriorated. Radiation-induced edema and radionecrosis occurred in 8.3% and 5% respectively. The median survival from the diagnosis of BM was 30 months. Repeat SRS is a safe and effective novel therapeutic approach to consider in carefully selected patients.