The risk of renal impairment in hormone-refractory prostate cancer patients with bone metastases treated with zoledronic acid.

BACKGROUND

Bisphosphonates have been used to treat bone metastases in hormone-refractory prostate cancer (HRPC), but certain agents have been associated with renal toxicity. For this observational study, the authors assessed the risk of renal impairment in patients with HRPC who received zoledronic acid from December 1999 to April 2005.

METHODS

A comprehensive medical records review was performed in a major tertiary oncology center (n = 122 patients). The primary outcome of renal impairment was defined as an increase >or=0.5 mg/dL or >or=1.0 mg/dL over baseline creatinine value if the baseline value was <1.4 mg/dL or >or=1.4 mg/dL, respectively. A risk factor analysis was conducted using the Andersen-Gill extension to the Cox proportional hazards model.

RESULTS

Renal impairment was observed in 23.8% of patients. The risk of renal impairment increased with an extended duration of zoledronic acid therapy (<6 months, 11.1%; >or=24 months, 26.3%) and previous pamidronate treatment (45.5% vs 19.0% for patients with no prior pamidronate). A significantly greater risk of renal impairment was associated with increasing age at zoledronic acid initiation, prior pamidronate use, and a history of renal disease, hypertension, or smoking (P <or= 0.05).

CONCLUSIONS

In an outpatient clinic setting, the risk of renal impairment among patients with HRPC who received zoledronic acid was greater than the risk reported previously in clinical trials.