Introduction
Post-operative stereotactic radiosurgery (PoSRS) following resection has become the standard of care for appropriate brain metastases. However high rates of leptomeningeal disease (LMD) after PoSRS have been reported. Neoadjuvant radiosurgery (NaSRS) has been proposed as an alternative treatment approach to decrease this risk. NaSRS may stimulate anti-tumour immune factors and effectively integrate with systemic therapy. Hypofractionated SRS (hf-SRS) is utilised to achieve a higher biologically equivalent dose (BED). The aim of this study was to report our experience of NaSRS in the hf-SRS setting.
Methods
Patients undergoing NaSRS were included in our study. Exclusion criteria included previous local treatment to the target lesion and ECOG≥3. Outcomes included local control (LC), distant control (DC), overall survival (OS), LMD and radionecrosis (RN).
Results
There were 32 patients and 33 lesions eligible for analysis. The mean age was 63.4 years old (range 43-80) with a male predominance (53%). The median time to follow up was 8.4 months (IQR 3.3-13.0). At the time of NaSRS, 21 patients (63.6%) were on systemic therapy. Hf-SRS was utilised in 19 lesions (57.6%). The median PTV was 4.50mm3 (IQR 3.27-9.36mm3). The median time from the final date of SRS to resection was one day (IQR 1-5). The 12-month LC rate was 95.2% (95% CI 86.1%-100%). The 12-month LMD rate was 3.0% (95% CI 0-12.1%). The 12-month RN rate was 6.2% (95% CI 0-18.1%). The 12-month DC rate was 49.1% (95% CI 28.3%-69.8%). The 12-month OS rate was 57.3% (95% CI 38.0-76.5%)
Conclusion
Our study is one of the largest NaSRS cohorts worldwide and the largest employing a hf-SRS technique. We observed low rates of LMD compared to previous PoSRS literature. We were able to achieve similar, and even improved, local control due to a higher BED with a fractionated approach as well as sparing normal brain tissue. There may also be advantages in regards to tumour immunology with NaSRS and concurrent systemic therapy.