According to the FDA approval label, zoledronic acid (Zometa) should be administered to men with advanced prostate cancer once they have failed one hormone therapy type, in other words, once the cancer has become castrate resistant.
Researchers at the Centre Hospitalier de i’Université de Montréal, Hôpital Notre-Dame, Montréal, Quebec, Canada evaluated the effect of zoledronic acid (zometa) on skeletal-related event (SRE) incidence as determined by the bone pain levels at study entry.
Bone metastases can destabilize skeletal integrity before the onset of symptoms, so they reasoned that treating patients before symptom onset might be more effective in preventing SREs and improving the quality of life. Zometa has demonstrated its ability to significantly reduce SREs as well as pain compared to placebo in men with advanced prostate cancer, thus it is the standard of care.
The researchers performed a placebo controlled, Phase III trial of men with castration-resistant prostate cancer, randomized to receive zometa 4 mg (n = 214) or placebo (n = 208) for ? 24 months. Their reported pain or no pain at baseline stratified the subjects. Bone pain was assessed at baseline, week 3, and week 6 and at 6-week intervals thereafter. The primary endpoint was the proportion of patients with ? 1 SRE.
1- Zometa significantly reduced the mean pain scores compared with placebo at 3, 9, 21, and 24 months (P ? .03 for each point) as well as reducing the annual incidence of SREs.
2- Among patients without baseline pain, Zometa decreased the percentage of men with ? 1 SRE by 39% and reduced the annual incidence of SREs by 49% compared with placebo.
3- Zometa delayed the onset of bone pain in those men without pain at baseline compared with placebo.
Zometa reduced bone pain and SREs compared with placebo in men with bone metastases from castration-resistant prostate cancer, irrespective of the baseline pain status, and appeared more efficacious when initiated before the onset of pain.
Reference: Urology. 2010 Nov;76(5):1175-81.
Pub Med: PMID: 21056263
Joel T Nowak, M.A., M.S.W.