CARBOMETASPINE: protocol for a multicenter, prospective, randomized controlled trial of carbonfiber spinal fixation in metastatic disease

Spinal metastases frequently cause neurological compromise and mechanical instability. Titanium fixation limits postoperative imaging and hinders stereotactic body radiotherapy (SBRT) planning because of artefacts. CARBOMETASPINE is a multicentre, prospective, randomised controlled trial. A total of 226 adults with unstable or epidurally infiltrating spinal metastases will be randomised 1 : 1 : 1 to: (I) carbonfibre/PEEK fixation + postoperative SBRT (5 × 5 Gy); (II) titanium fixation + postoperative SBRT; (III) preoperative SBRT + titanium fixation. The primary endpoint is progressionfree survival of the treated spinal level. Secondary endpoints include dosimetric quality, pain (NRS), surgical complication rates and implant failure. Radiolucent carbonfibre implants may improve the geometric accuracy of SBRT planning and enhance local tumour control while preserving mechanical strength. This protocol follows SPIRIT recommendations and will provide robust evidence on clinical benefits and implementation barriers of carbonfibre systems. ClinicalTrials.gov, NCT06293157. Registered 17 February 2024.