Osteoclast inhibition by pamidronate in metastatic prostate cancer: a preliminary study.

Twenty five hormone manipulated patients with prostate cancer and metastatic bone disease, treated at least 6/12 previously by hormone manipulation, were given intravenous infusions of Disodium Pamidronate (APD) over a 6 month period. Patients received 30 mg weekly for 4 weeks then twice monthly for 5 months. No other treatment was administered during study. Eleven of 17 patients with pain at the start of the study were pain free at the end. Fasting morning calcium excretion and serum osteocalcin fell significantly with Pamidronate (P less than 0.0001) and urine hydroxyproline was lowered in 13/20 evaluable patients at 6 months. Alkaline phosphatase fell in a proportion of patients and five of 17 patients with previously progressive bone scans stabilised (4) or regressed (1) on treatment. Rising acid phosphatase levels were also lowered in five patients. It is concluded that Pamidronate may be effective in palliating bone pain in some patients and has a stabilising influence on abnormally high bone turnover in metastatic prostate cancer. Further controlled studies of the compound are now warranted.