The aim of this study is to determine if 3 monthly infusions of zoledronic acid, given over one year, improves the bone mineral density in osteoporotic patients undergoing androgen deprivation therapy for prostate cancer

Androgen Deprivation Therapy is the mainstay of treatment for advanced prostate cancer. However they are associated with accelerated bone loss, osteoporosis and fractures. Previous studied looking at the use of zoledronic acid have predominantly studied men with a normal or osteopenic bone mineral density. However, it has been shown that upto 40% of men presenting with prostate cancer have osteoporosis and it is these who are at most risk of osteoporotic fractures. Our aim was to evaluate the efficiency of zoledronic acid in 2 groups of osteoporotic patients, those undergoing treatment with LHRH agonists and with antiandrogens.Peripheral and axial bone densitometry will be used to measure percentage changes in bone mineral density over 3 years. The first year with the patients on LHRH or antiandrogen, the second year continuing with their androgen deprivation therapy and zoledronic acid. Then bone mineral density will be measured one year following the last infusion of zoledronic acid to ascertain the optimum frequency of administration.

The study will also involve monitoring serum and urine bone turnover markers.

Inclusion Criteria:

• patients with locally advanced prostate cancer who progress from normal/ osteopenic bone mineral density to osteoporosis while on LHRH agonists (LHRH Group). Also patients who have been commenced on Bicalutamide due to osteoporosis at presentation (Bicalutamide Group)

Exclusion Criteria:

• patients with elevated prostate specific antigen, any illness or medication that would affect bone and mineral metabolism, previous bisphosphonate treatment, severe hepatic or renal insufficiency.