Comparing Frame-Based to Mask-Based Stereotactic Radiosurgery in Metastatic Brain Disease: A Meta-Analysis of 1,003 Patients

Introduction: Metastasis is the most common cause of intracranial tumors in adults. Clinical trials support the use of Stereotactic Radiosurgery (SRS) as the primary treatment for patients with limited numbers of small brain metastases. Head fixation is usually performed with framed-based (FB) fixation; however, less invasive approaches like mask-based (MB) fixation have emerged as an alternative. This represents the first meta-analysis assessing clinical outcomes between both approaches.

Methods: Databases were searched until August 28th, 2023, to identify studies comparing the efficacy of MB to FB SRS in the treatment of brain metastases. Our primary outcome was 1-year local tumor control. Secondary outcomes included treatment time (TT), comfort, and tumor progression. Odds ratio (OR), risk ratio (RR), and hazard ratio (HR) were used for statistical comparisons.

Results: From 290 articles initially identified, a total of 9 retrospective studies (2 clinical trials) involving 1,003 patients were included. The 1-year local tumor-control rate favored the FB group (RR=0.87[0.78-0.96], p=0.005). Local control rates at ≥6 months were similar among observational (RR=0.95[0.89-1.01], p=0.12) and clinical trials (RR=0.89[0.69-1.16], p=0.40). Tumor progression was similar among the groups (HR=0.72[0.41-1.25], p=0.24). Higher comfort rates were associated with the use of MB SRS (OR=6.36[3.28-12.35], p= < 0.00001). TT was similar across groups (mean difference=-16.98 minutes[-47.90-13.93 minutes], p=0.28).

Conclusion : While MB fixation is a more comfortable option, while observational studies suggest that local tumor control is higher when FB fixation is used, this difference was not conclusive when analyzing clinical trials. Further well-designed clinical trials are needed to evaluate optimal treatments for metastatic brain disease.