Purpose: Bisphosphonates have been reported to be effective in reducing bone pain and skeletal-related events associated with bone metastases in hormone-refractory prostate cancer (HRPC). However, whether bone resorption is reduced primarily by these particular drugs is difficult to evaluate because patients with HRPC are usually treated with secondary or tertiary hormonal manipulations including second-line antiandrogens, high-dose diethylstilbestrol, or low-dose dexamethasone therapies, some of which may also be effective. Thus, we assessed changes in the level of the carboxyterminal telopeptide of type-I collagen (ICTP), a bone resorption marker, before and after pamidronate administration in HRPC patients with increasing prostate-specific antigen (PSA) levels.
Patients and methods: Twenty-one HRPC patients with bone metastases and increasing PSA levels were intravenously treated with pamidronate at a dose of 30 mg either every 2 or every 4 weeks. Pamidronate administration was started immediately after confirmation of three consecutive increases in the PSA level.
Results: In 14 patients (67%), the ICTP levels decreased after the administration of pamidronate, despite increasing PSA levels. In 7 of these cases, the ICTP levels were lower than those recorded for 6 months or longer before the start of pamidronate administration. The characteristics of the responders were compared with those of the non-responders.
Conclusion: In 67% of the HRPC patients with increasing PSA levels, pamidronate reduced the accelerated turnover of bone metabolism caused by metastases of prostate cancer.