Comparative effectiveness of frame-based and mask-based Gamma Knife stereotactic radiosurgery in brain metastases: A 509 patient meta-analysis

Stereotactic Radiosurgery (SRS) is the primary treatment for patients with limited numbers of small brain metastases. Head fixation is usually performed with framed-based (FB) fixation; however, mask-based (MB) fixation has emerged as a less invasive alternative. A comparative meta-analysis between both approaches has not been performed.

Databases were searched until August 28th, 2023, to identify studies comparing MB and FB SRS in the treatment of brain metastases. Our outcomes of interest included local tumor control (LTC), radiation necrosis (RN), mortality, and treatment time (TT). Mean difference (MD), risk ratio (RR), and hazard ratio (HR) were used for statistical comparisons.

From 295 articles initially identified, six studies (1 clinical trial) involving 509 patients were included. LTC revealed comparable RR at 6-months (RR = 0.95[95%CI = 0.89–1.01], p = 0.12) and a marginal benefit in FB SRS at 1-year (RR = 0.87[95%CI = 0.78–0.96], p = 0.005). However, in oligometastases exclusively treated with single-fraction SRS, LTC was similar among groups (RR = 0.92 [95%CI = 0.89–1.0], p = 0.30). Similarly, in patients with oligometastases treated with single-fraction SRS, RN (HR = 1.69; 95%CI = 0.72–3.97, p = 0.22), TT (MD = -29.64; 95%CI = -80.38–21.10, p = 0.25), and mortality were similar among groups (RR = 0.62; 95%CI = 0.22–1.76, p = 0.37).

Our findings suggest that FB and MB SRS, particularly oligometastases treated with single-fraction, are comparable in terms of LTC, RN, TT, and mortality. Further research is essential to draw definitive conclusions.