PROSTATE CANCER;

Background: Androgen deprivation therapy (ADT) with luteinizing hormonereleasing hormone agonists (LHRHa) is a major treatment modality for prostate cancer (PC),particularly advanced disease. LHRHa induced hypogonadism promotes bone loss, leading toosteoporosis and heightened fracture risk. Most previous studies on skeletal impact of LHRHaemployed bone mineral density (BMD) testing. Serum bone-specific alkaline phosphatase(BSAP), an established bone biomarker, is reflective of changes in skeletal metabolism whichprecede BMD changes. In postmenopausal women, serum BSAP has been associated withfracture risk irrespective of BMD. Setting: Charing Cross Hospital, London, United Kingdom.Methods: We assessed early changes in serum BSAP levels of patients with non-metastaticPC (n=9) undergoing LHRHa therapy. Serum testosterone and estradiol concentrations werealso measured. Samples were taken at baseline before the start of treatment and three monthsafterward. Comparisons were made with blood samples taken at similar time points for agematchedcontrols without PC (n=9). Results: No significant difference in BSAP levels wasseen between groups (p=0.242). Testosterone and estradiol levels were significantly reducedfollowing treatment (p=0.000). No correlation was observed between serum BSAP and serumtestosterone (R=0.187, p=0.276) or serum estradiol (R=0.055, p=0.75). Conclusions:Changes in serum BSAP levels may not be evident as early as 3 months following ADT withLHRHa. The study was limited by the small sample size and use of serum BSAP only whichis one of the many bone markers. A larger study using multiple bone markers is warranted todetermine early effects of LHRHa treatment on bone metabolism.