Mask-based vs. frame-based stereotactic radiosurgery: A systematic review

Stereotactic radiosurgery (SRS) has been demonstrated over more than 30 years to be a safe and effective treatment for a variety of central nervous system disorders, including brain metastases. Traditionally, SRS delivery has required placement of a Leksell frame prior for treatment planning. Although highly accurate, frame placement introduces issues in workflow and patient comfort. In response to these constraints, a new innovative SRS delivery system-Gamma Knife Icon-was developed to support a frameless mask-based technique. The relative benefits of frame- or mask-based SRS remain incompletely understood. Mask- or frame-based SRS were the compared treatment modalities. Tumor control was the primary outcome; adverse radiation effects (AREs; e.g., radiation necrosis) and dosimetric parameters were the secondary outcomes. PRISMA-compliant systematic review of three databases (PubMed, Google Scholar, OVID Medline) from inception through 12/31/2022. Predetermined inclusion criteria were quantitative data analysis, direct comparison between mask- and frame-based SRS techniques, and outcomes including either tumor control or AREs. To limit confounding by fractionation scheme, inclusion was also limited to cohorts with separate explicit data on single-fraction treatment plans. Abstract screening yielded 24 candidate manuscripts for full-text review; 5 publications met all criteria and were included. All 5 studies failed to detect a difference in tumor control or AREs between mask- and frame-based SRS techniques. Mask-based SRS may offer a more convenient treatment for brain metastases, with comparable efficacy to frame-based SRS. Given the congruent findings between preceding observational data, one RCT, and the present meta-data, mask-based SRS may be considered the front-line technique for brain metastases.