# Local Control After Adjuvant Radiosurgery for Spinal Metastasis Treated With Decompression and Posterior Segmental Stabilization: A Comparison Between Carbon Fiber/Polyetheretherketone-Based and Metallic Implants

## TL;DR

This study compares carbon fiber and titanium spinal implants in patients with spinal metastasis who received surgery and radiation, finding that carbon fiber implants may be linked to better local tumor control.

## Contribution

The study evaluates the impact of carbon fiber-reinforced polyetheretherketone (CFRP) versus titanium implants on local tumor control and hardware durability after spinal surgery and radiosurgery.

## Key findings

- CFRP implants showed a trend toward lower local tumor progression compared to titanium implants.
- Higher equivalent radiation dose was significantly associated with better local tumor control.
- No significant differences in hardware durability were observed between the two implant types.

## Abstract

Carbon fiber-reinforced polyetheretherketone (CFRP) spinal implants are gaining popularity in the surgical management of spinal metastasis because of their physical and radiographic properties, which facilitate adjuvant radiation planning and tumor surveillance. Their impact on clinical outcomes is still under investigation. We evaluated the role of hardware material (CFRP vs titanium) in local control and hardware durability in metastatic cases receiving decompressive surgery and adjuvant spinal stereotactic radiosurgery (SSRS).

This single-institution, retrospective cohort study was approved by the local institutional review board. Patients who underwent decompressive surgery with posterior segmental instrumentation followed by treatment with SSRS for metastatic spine disease were included. Exclusion criteria were as follows: (1) cervical implants, (2) mixed-type hardware, (3) SSRS greater than 60 days after surgery, and (4) less than 3 months magnetic resonance imaging follow-up. Only tumor progression occurring inside or at the margins of the irradiated field was considered.

Eighty-three spinal segments (55 titanium, 28 CFRP; from 82 patients) were evaluated. Except for the number of radiation fractions, proportion of single-fraction 24 Gy cases, and radiation equivalent dose in 2-Gy fractions, no significant differences were found between groups. The median follow-up time was 14.5 months (range, 3.0-70.4 months). Sixteen local progressions were identified, with 15 in the titanium group (P = .009). Using death as a competing factor, local progression-free survival was longer in the CFRP group (HR, 0.127; 95% CI, 0.017-0.945; P = .044). The median time to progression was 9.27 months (IQR, 4.5-15.65 months). Higher equivalent dose in 2-Gy fractions was the only variable associated with local tumor control in both univariate and multivariate analyses (P = .025 and P = .019, respectively). The titanium cohort experienced 4 hardware adverse events, whereas the CFRP group had 2 adverse events (P > .05).

CFRP implants were associated with lower rates of local progression in crude analyses, but did not reach statistical significance in multivariable models. No differences in hardware durability were identified.