CORRESPONDENCE

Re: A Randomized, Placebo-Controlled Trial of Zoledronic Acid in Patients With Hormone-Refractory Metastatic Prostate Carcinoma

Mark Rosenthal

Correspondence to: Mark Rosenthal, Ph.D., F.R.A.C.P., Department of Medical Oncology, Royal Melbourne Hospital, Parkville, Victoria, Australia 3050 (e-mail: mark.rosenthal{at}mh.org.au).

Bisphosphonates such as zoledronic acid have an increasing role in the treatment of patients with bone metastases. The study by Saad et al. (1) suggests that zoledronic acid reduces skeletal-related events in patients with metastatic prostate cancer.

Although Saad et al. (1) clearly define "skeletal-related events," the authors do not indicate clinical relevance. The only skeletal-related event to achieve a statistically significant difference was that of pathologic fracture. However, it is unknown how many of these pathologic bone fractures had a clinically significant impact. Indeed, the equivalent incidence of radiation therapy to bone across the treatment arms suggests that not all fractures were clinically relevant. Similarly, the other primary endpoints suggesting a therapeutic reponse to the clinical problem of pathologic fracture, such as change in neoplastic treatment and surgery to bone, were not different between treatment arms. In addition, the incidence of spinal cord compression was unaltered between treatment arms, further suggesting that pathologic fractures did not necessarily result in clinically important complications.

The study by Saad et al. (1) also clearly demonstrates that zoledronic acid has no effect on other important clinical parameters, including quality of life, progression-free survival, and overall survival. The authors highlight the statistically significant effect of zoledronic acid on pain scores but do not address the paradox that there was no concurrent increase in the analgesics required by those patients with worse pain.

In conclusion, the study by Saad et al. (1) documents that zoledronic acid can provide statistically significant radiologic benefits to patients with metastatic prostate cancer. However, there is little, if any, demonstrable clinical benefit identified for the same patients, raising the question of whether zoledronic acid should become a standard of care for patients with metastatic prostate cancer.

REFERENCE

1 Saad F, Gleason DM, Murray R, Tchekmedyian S, Venner P, Lacombe L, et al. A randomized, placebo-controlled trial of zoledronic acid in patients with hormone-refractory metastatic prostate carcinoma. J Natl Cancer Inst 2002;94:1458–68.[Abstract/Free Full Text]



             
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