Radiologic and clinical changes after denosumab treatment for giant cell tumors of the mobile spine: a quantitative study

OBJECTIVES: To analyze the radiologic and clinical changes after denosumab treatment in patients with giant cell tumors (GCTs) in the mobile spine. METHODS: Clinical data and images by computed tomography and magnetic resonance imaging at a single center were retrospectively reviewed before and after denosumab treatment. RESULTS: Pre- and post-treatment data from 24 patients were evaluated. On imaging, marginal ossification and/or bone formation was observed in 22 patients (91.7%). The median maximum diameter of the GCT reduced from 52.5 to 48.2 mm (p < 0.001), and the mean proportion of tumor to spinal canal area decreased from 36.8 to 18.5% (p < 0.001). Out of six patients with compression, three patients (50%) showed no compression after treatment. The signal intensity (SI) ratio between the solid part of the tumor and the normal spinal cord on T2-weighted MR images was 0.77 ± 0.22 and decreased to 0.58 ± 0.22 (p = 0.001). On clinical symptoms, the mean visual analog scale scores were reduced from 5.3 to 2.0 (p < 0.001) and the Karnofsky Performance Scale scores increased from a median of 65 to 80 (p < 0.001). Post-treatment, performance scores improved in eight patients (33.3%) (p = 0.003), and the neurological function of four patients improved according to Frankel grade (p = 0.046). CONCLUSIONS: Bone formation, tumor reduction, regression of epidural lesion and the decrease in SI ratio on T2-weighted image should be considered as the effectiveness of denosumab in the treatment of spinal GCT. In clinical application, denosumab can relieve pain, improve neurological function, and improve the quality of life of spinal GCT patients.