Possible bone-preserving capacity of high-dose intramuscular depot estrogen as compared to orchidectomy in the treatment of patients with prostatic carcinoma

BACKGROUND: Treatment of prostatic disease with GnRH agonists or by orchidectomy affects bone mass negatively. Estrogen treatment has beneficial effects on bone mass in women and might hypothetically have a bone preserving capacity also in patients with prostatic cancer. METHODS: We followed serum markers for bone and collagen metabolism and sex steroids for 18 months in patients with prostatic cancer treated by orchidectomy (N = 13) or by single-drug parenteral polyestradiol phosphate (240 mg intramuscularly every second week for the first two months, and then every fourth week; N = 17). RESULTS: Total and free testosterone reached castration levels within 1.5 months of estrogen treatment. Four patients developing progressive disease and/or signs of metastasis were excluded from the analysis. In the remaining patients, serum osteocalcin, procollagen IIIP (PIIINP), procollagen (PICP), and the crosslinked carboxyterminal telopeptide of type I collagen (ICTP) increased significantly over time following orchidectomy (N = 11). Serum osteocalcin and PICP decreased significantly over time during estrogen treatment (N = 15). Treatment values of all four markers were significantly lower in estrogen-treated than in orchidectomized patients. CONCLUSIONS: The changes in serum bone and collagen markers indicate an increased bone turnover in orchidectomized subjects. The opposite pattern was found in the estrogen-treated patients, indicating a reduced turnover. Estrogens may also have a bone mass-preserving capacity in elderly males with prostatic cancer.