The Risk Of Renal Impairment In Hormone-Refractory Prostate Cancer Patients With Bone Metastases Treated With Zoledronic Acid

April 30, 2007 – 12:53 pm | posted in Clinical Trials / Drug Trials, Men's health, Prostate, Urology / Nephrology

UroToday.com- Nearly one-quarter of prostate cancer (CaP) patients treated with zoledronic acid (ZA) suffer renal impairment according to a report by Dr. Oh and colleagues in the online version of Cancer.

ZA is an intravenous bisphosphonate given to decrease skeletal related events in CaP patients with bone metastases. In a phase III trial, ZA was associated with renal impairment in 17% of cases. The present study is the first observational study that quantifies the rate or renal impairment and identifies associated risk factors. Renal impairment in this analysis was defined as any one of the following; an increase in the serum creatinine of >0.5mg/dL over the initial level for initial values <1.4mg/dL, or an increase of >1.0mg/dL over the initial level for initial values >1.4mg/dL. Secondary definitions of renal impairment included severity degrees of calculated creatinine levels.

The records of treated patients at the Dana-Farber Cancer Institute and the Brigham and Women’s Hospital, Boston were reviewed and yielded 122 evaluable patients. Median patient age at the time of treatment was 71 years and 94% were white. The median observation period was 11.7 months. Ninety-one percent had a baseline serum creatinine of <1.4mg/dL and the median was 1.0mg/dL. The median treatment period for ZA was 9.8 months, with a median of 8 infusions per patients. Discontinuation of ZA occurred in 72 patients (59%), of whom 24 died from CaP.

A total of 29 of 122 patients (23.8%) experienced >1 renal impairment event during treatment, with almost all of these patients having had normal renal function at baseline. A decline in creatinine clearance was observed in 51 men (42%). Duration of treatment with ZA was associated with the endpoint; an 11% rate of renal impairment in those treated with ZA <6 months compared to 26% in those treated for >2 years. These numbers rose to 24% and 37%, respectively when calculated creatinine clearance was used. Neither of these methodologies, however, was statistically significant. Other variables that were associated with renal impairment were previous pamidronate treatment (46% vs. 19% for patients with no prior pamidronate), increasing age at time of ZA treatment, and a history of renal disease, hypertension or smoking.

The administration of ZA must be adjusted for renal insufficiency and the potential for renal impairment taken in context with its significant cancer related benefits.

William K. Oh, Kevin Proctor, Mari Nakabayashi, Carolyn Evan, Lauren K. Tormey, Timothy
Daskivich, Lucia Antràs, Michael Smith, Maureen P. Neary, Mei Sheng Duh

Cancer Volume 109, Issue 6, Date: 15 March 2007, Pages: 1090-1096
Reviewed by UroToday.com Contributing Editor Christopher P. Evans, MD

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