Combined Post-operative Denosumab and Oral Bisphosphonate Therapy Following Resection of Spinal Giant Cell Tumor: A Case Report.

Introduction: Giant cell tumor (GCT) of the spine is a rare, locally aggressive bone tumor with a high risk of recurrence, particularly when wide surgical margins cannot be achieved. Although en bloc spondylectomy provides the best oncological control, it is frequently not feasible due to anatomical constraints. Systemic adjuvants have therefore been explored to reduce recurrence risk. Denosumab suppresses osteoclast-mediated bone resorption, while bisphosphonates exert direct anti-tumor effects on neoplastic stromal cells. However, the intentional combined post-operative use of denosumab and oral bisphosphonate therapy in spinal GCT (SGCT) has not been previously reported. This case highlights the feasibility and biological rationale of this combined adjuvant strategy. Case Report: A 27-year-old male presented with severe low back pain and bilateral lower limb radicular pain of 6 months' duration. Imaging demonstrated a destructive lesion involving the third lumbar vertebral body with paravertebral soft-tissue extension. A diagnosis of Enneking stage III GCT was made after biopsy. The patient received pre-operative denosumab followed by gross total resection of the affected vertebra with posterior stabilization and anterior column reconstruction. Postoperatively, denosumab therapy was continued for 6 months, and the patient was simultaneously commenced on oral bisphosphonate therapy (weekly alendronate followed by monthly ibandronate). The patient had complete resolution of symptoms. Serial imaging demonstrated progressive osseous consolidation and stable instrumentation with no evidence of residual or recurrent disease. At 4½ years of follow-up, the patient remained radiologically disease free without treatment-related adverse events. Conclusion: This report demonstrates the feasibility of combining post-operative denosumab and oral bisphosphonate therapy as an adjuvant strategy for high-risk SGCT when wide surgical margins are not achievable. By targeting different cellular pathways involved in tumor biology, this approach may provide complementary tumor control, thereby reducing the risk of recurrence.