Effects of combined androgen blockade on bone metabolism and density in men with locally advanced prostate cancer

Objective: To investigate whether combined androgen blockade (CAB) produces any adverse effects on bone metabolism and mineral density in patients with locally advanced prostate cancer.Materials and methods: The study group consisted of 17 stage T4 prostate cancer patients treated with CAB and had no evidence of bone metastasis on bone scintigraphy. The mean duration of CAB and final total prostate specific antigen (PSA) level at the time of study were found at 28.5 ± 15.9 (6–58) months and 0.39 ± 0.5 (0.1–2) ngml, respectively. Twenty age and socioeconomically matched benign prostate hyperplasia (BPH) patients were taken as the control group. Both groups were compared with regard to lumbar bone mineral density (LBD), femur bone mineral density (FBD) and serum parameters of bone metabolism namely calcium (Ca), phosphate (P), magnesium (Mg) and alkaline phosphatase (ALP). Bone mineral density was measured with dual energy x-ray absorptiometry.Results: The mean FBD, LBD and serum Ca, P, Mg and ALP measurement of the patients treated with CAB were 0.85 ± 0.1 g/cm², 1.16 ± 0.2 g/cm², 9.1 ± 0.3 mg/dl, 3.6 ± 0.6 mg/dl, 1.95 ± 0.14 mg/dl, 187.5 ± 61 mg/dl, respectively. No significant difference was found between patients subjected to CAB and the age matched controls in any of the studied parameters namely age, FBD, LBD, Ca, Mg and ALP except serum phosphate. Serum phosphate levels were significantly (p =0.001) higher in patients treated with CAB suggesting a minor effect of CAB on bone metabolism.Conclusion: No convincing evidence was found about the detrimental effect of CAB on bone mineral density and metabolism in a highly selected group of patients with advanced prostate cancer without bone metastases.