Long-term efficacy and safety of pamidronate disodium in treatment of bone metastases in breast cancer

To evaluate the long-term efficacy and safety of pamidronate disodium in patients with bone lesions secondary to advanced breast carcinoma. A retrospective chart review was conducted of 62 patients receiving intravenous pamidronate disodium for metastatic breast cancer. The proportion of patients experiencing at least one skeletal related event (SRE) after 12 months of therapy was determined. The proportion of patients who had an SRE was 29.00% (18 individuals) and the median time to first event was greater than 350 days. Radiotherapy(11 individuals)and pathologic fracture(6 individuals)were the most frequent type of SRE, while cord compression(1 individuals) and hypercalcaemia(0 individuals) were rare. A total of 37 individuals had transient hypocalcaemia without any clinical symptom. No significant creatinine abnormalities were encountered. There were no clinically relevant changes of calcium, phosphate and creatinine before and after therapy. Long-term treatment with pamidronate disodium significantly reduces and delays skeletal morbidity from osteolytic metastases. Prolonged therapy was well tolerated. This study suggests that the rate of clinically relevant SREs is substantially lower than the event rate observed in phase III clinical trials.