TRACP-5b for Diagnosis and Follow-up of Giant Cell Tumor of Bone

This prospective observational study will evaluate whether the blood biomarker TRACP-5b can help diagnose and monitor patients with giant cell tumor of bone (GCTB). GCTB is a rare but locally aggressive bone tumor that can return even after surgical treatment. Currently, patients require long-term follow-up based mainly on imaging examinations such as CT or MRI, and suspected recurrence often requires invasive biopsy procedures. TRACP-5b is an enzyme associated with osteoclast activity that can be measured from a blood sample. Previous studies suggest that TRACP-5b levels may reflect disease activity and risk of recurrence in patients with GCTB. In this study, patients with newly diagnosed GCTB and patients already undergoing long-term follow-up after treatment will undergo regular blood sampling for TRACP-5b measurement during routine outpatient visits. Laboratory results will be compared with the patient's clinical condition, imaging findings, and histological results when available. The goal of the study is to determine whether TRACP-5b could become a reliable and minimally invasive tool for earlier detection of disease recurrence and improved long-term monitoring of patients with giant cell tumor of bone.