Efficacy of neoadjuvant stereotactic radiosurgery in solid cancer brain metastases: a systematic review and metanalysis.

Background: Neoadjuvant stereotactic radiosurgery (NaSRS) is a novel strategy for brain metastasis (BMs) management, promising to achieve lower rates of toxicity, leptomeningeal progression, and high percentage of local control. Material and Methods: An extensive systematic literature review and meta-analysis of proportions were performed. A total of 8 papers were eligible for final analysis after searching MEDLINE via PubMed, Web-of-science, Cochrane Wiley, and Embase databases. Results:A total of 551 patients undergoing NaSRS to treat 583 lesions were included. Median age was 57.7 [56.5-61.1] years, with a median tumor volume of 9.1 [8.3-14.4] cc. The most frequent histology was non-small cell lung cancer (40.7%), followed by breast (20.5%), and melanoma (15.6%). Most of the lesions had a supratentorial location (77.6%). Treatment parameters were homogenous across the studies and showed a median dose of 16 [14.9-20.5] Gy at 80% isodose.Surgery was performed after a median of 1 [1-2] day and achieved gross-total extent in 92.4% of cases. Median follow-up was 12.9 [9.9-18.9] months.Pooled proportion of patients showed an overall mortality rate of 50% (CI 37-63; I2=87%), local failure of 15% (CI 12-20%; I2=12.1%) and a rate of distant brain failure of 42% (CI 35-49%; I2=55.3%). The median local progression-free survival (PFS) was 10.4 months, while median survival without distant failure was 8 months.Rate of radionecrosis (RN) and leptomeningeal dissemination (LMD) were 4% respectively. Median overall survival (OS) was 14.4 months. Conclusion: Existing data suggest that NaSRS achieves good local control on BMs with relatively lower dose than adjuvant treatment and low incidence of RN and other complications. These results need to be confirmed by larger studies with higher level of evidence to address formal comparisons with other regimens.