Pamidronate-induced kidney injury in a patient with metastatic breast cancer.

The American Society of Clinical Oncology recommends bisphosphonate use, such as intravenous pamidronate, for women with breast cancer who have radiographic evidence of bone destruction. However, pamidronate therapy has been associated with the development of the nephrotic syndrome. This renal abnormality has been posited to be due to a number of different mechanisms, including collapsing focal segmental glomerulosclerosis (FSGS). We present one such case of a patient who developed collapsing FSGS with nephrotic-range proteinuria after treatment with pamidronate for osteolytic bone metastases from an infiltrating ductal carcinoma of the breast. A possible mechanism of this kidney injury is mitochondrial apoptosis in podocytes and/or proximal tubular cells, which has been shown to occur in a dose-dependent fashion in experimental models. Renal prognosis is very poor if collapsing FSGS develops. Thus, prevention or early detection rather than effective therapy should be the primary consideration.