Adjuvant Zoledronic Acid in High Risk Giant Cell Tumour of Bone (GCT)

Inclusion Criteria: * Signed written informed consent * Male or female \> 18 years of age * Histologically proven GCT treated with surgery * High risk GCT defined as minimal one or more of the following: * Recurrent GCT * GCT located in the pelvis, sacrum, spine, distal ulna or growth in soft tissue * GCT grade III * Pathological fracture in GCT * Absence of local adjuvant therapy (cryosurgery or phenol instillation) * Neutrophils \> 1.5x109/L, platelets \> 100x109/L, and Hb \> 6 mmol/l * Bilirubin level \< 1.5 x ULN * ASAT and ALAT \< 2.5 x ULN * Adequate renal function as defined by: serum creatinine clearance \> 60 cc/min * Expected adequacy of follow-up Exclusion Criteria: * Unresectable or metastatic GCT and grade IV GCT * Prior bisphosphonate usage, except preoperative treatment with zoledronic acid up to 3 months before surgery * Other previous malignancy within 5 years, with exception of a history of a previous basal cell carcinoma of the skin or pre-invasive carcinoma of the cervix * Known hypersensitivity reaction to any of the components of the treatment * Pregnancy or lactating * Medical or psychological condition which in the opinion of the investigator would not permit the patient to complete the study or sign meaningful informed consent