Adding zoledronic acid to androgen deprivation therapy (ADT) does not significantly prolong time to treatment failure in men with treatment-naïve prostate cancer and bone metastasis, according to a new study conducted in Japan.
The combination, however, may delay development of castration-resistant disease in patients with lower baseline PSA levels.
Tomomi Kamba, MD, of Kyoto University, and colleagues enrolled 227 men with treatment-naïve prostate cancer (PCa) and bone metastasis, randomly assigned them to receive either combined ADT alone or combined ADT plus zoledronic acid (ZA). The median follow-up was 41.5 months.
The median time to treatment failure (TTTF) was similar for the combined ADT and the ADT/ZA groups (12.4 and 9.7 months, respectively), the researchers reported online ahead of print in the International Journal of Clinical Oncology. For men with baseline PSA levels below 200 ng/mL, the median TTTF was 9.8 and 23.7 months for the combined ADT and ADT/ZA groups, respectively, a significant difference that corresponded to a 42% decreased risk of treatment failure in the ADT/ZA recipients.
The median time to the first skeletal-related event was significantly longer for ADT/ZA group than the combined ADT group (64.7 vs. 45.9 months), a difference that corresponded to a 42% decreased risk of skeletal-related events for the ADT/ZA group. Overall survival was similar between the treatment arms.