Pamidronate and zoledronic acid (bisphosphonates) are a mainstay in the treatment of men with advanced prostate cancer as well as for breast cancer survivors for the prevention of skeletal-related events (SREs). There have been many clinical trials comparing the efficacy and side effect profiles between pamidronate and zoledronic acid among men with advanced prostate cancer.

A retrospective cohort study was conducted, using data from Kaiser Permanente’s Southern California Region. The subject cohort included men aged >/=18 years diagnosed with prostate cancer from 1998 to 2004 who received at least 1 infusion of either pamidronate or zoledronic acid after their cancer diagnosis. Any man receiving both drugs and those with a documented SRE prior to diagnosis were excluded from the study.

The primary outcome of SREs was defined using diagnosis codes for fractures, spinal cord compression, radiation to bone, and hypercalcemia of malignancy, the common SREs found in men with prostate cancer. Secondary outcomes were deterioration in renal function, based on serum creatinine laboratory results, and mortality.

Multivariate logistic regression was used to predict SREs and mortality risk for pamidronate compared to zoledronic acid. The proportion of patients with renal function deterioration was analyzed using chi(2) tests.

1- The cohort included 118 patients treated with pamidronate and 274 treated with zoledronic acid.

2- Results showed no significant difference in risk of SREs for pamidronate versus zoledronic acid (OR 0.99; 95% CI 0.59 to 1.67; p = 0.98).

3- No significant difference was found in renal function deterioration (chi(2) 2.08; p = 0.15) or mortality (OR 0.71; 95% CI 0.43 to 1.17; p = 0.18).

The study authors concluded that for men with prostate cancer, the choice between these bisphosphonates must be balanced between the shorter infusion times of zoledronic acid versus its increased costs. There was no evidence of any difference in outcomes.

PMID: 20682850 [PubMed – as supplied by publisher], Spence MM, Hui RL, Chan J, Schottinger JE.

Joel T Nowak, M.A., M.S.W.