Zoledronic acid and hormone therapy in prostate cancer with bone tumors

The authors determined the factors that affected survival in prostate cancer patients with bone tumors when treated with zoledronic acid (Zometa, INN, Reclast). 

Hormone therapy is commonly used to treat prostate cancer. It involves targeting the male sex hormones active in prostate cancer, such as testosterone. In more advanced stages of prostate cancer (stage III/ IV – cancer has spread outside of the prostate) tumors can form on the bones. Hormone therapy can be used in combination with other treatments, such as zoledronic acid, to treat bone tumors in prostate cancer patients. Zoledronic acid is given to patients who have weak or thin bones that break easily.

Bone-specific alkaline phosphatase (BAP – enzyme found in the blood indicating bone tumor growth) and prostate specific antigen (PSA – protein elevated in the blood when prostate cancer is present) can be used to determine the presence of prostate cancer and bone tumors. These are known as bone markers.

Further research is needed to determine the benefit of combining hormone therapy and zoledronic acid in prostate cancer patients with bone tumors. 

The authors aimed to determine the survival in prostate cancer patients with bone tumors treated with zoledronic acid and hormone therapy.

52 patients were analyzed in this study with a follow up time of 41.6 months. None of the patients received prior treatment for prostate cancer.

Patients were given 4 mg of zoledronic acid intravenously every 4 weeks for up to 24 months. In addition, patients were simultaneously given two hormone therapies – bicalutamide (Casodex – 80 mg daily, oral) and goserelin acetate (Zoradex – 10.8 mg every 12 weeks, injected under skin).

The average time to PSA progression (rise in PSA levels following treatment) was 25.9 months. High BAP was identified as an independent risk factor for time to PSA progression. Patients with high BAPs had a 6.51 times increased risk of experiencing a shorter time to PSA progression than patients with low BAPs. Patients with a BAP of more than 26 µg/L had an average time to PSA progression of 12.7 months.

Patients who had high levels of C-terminal telopeptide (ICTP) of type I collagen had 9.62 times increased risk of death. ICTP is a biological indicator found in the blood that measures the growth of new bones in the place of old bones. Patients with ICTP of more than 8 ng/ ml, had an overall survival (patients who were still alive following treatment) of 31.1 months.

The authors concluded that measuring bone markers such as BAP and ICTP might benefit previously untreated prostate cancer patients with bone tumors, who were subsequently treated with zoledronic acid and hormone therapy.

Data presented was from a small study group. So the results cannot be widely applied.