Estramustine affects bone mineral metabolism in metastatic prostate cancer

Abstract

A patient with metastatic prostate cancer is described where treatment with Adriamycin (doxorubicin) and estramustine produced severe hypophosphatemia (serum phosphate level, 1.2 mg/dl), which was reversible when treatment was discontinued. Previous studies have shown no effect of Adriamycin on serum phosphate levels. A retrospective study of serial serum chemistry values was done in 15 patients treated with estramustine. A significant fall in the serum phosphate level (mean, 0.8 ± 0.3 mg/dl) was observed during the first 6 weeks of treatment. When compared with similar patients treated with bilateral orchiectomy, estramustine‐treated patients had lower levels of serum calcium, fractional excretion of calcium, serum phosphate, and renal tubular threshold for phosphate reabsorption (TmPO4/GFR). Qualitatively similar but quantitatively smaller effects were also seen in a group of patients treated with diethylstilbestrol (DES) in a dose of 1 to 3 mg daily. Estramustine appears to have significant effects on bone mineral metabolism, particularly on renal phosphate handling resulting in significant hypophosphatemia. This is probably due to an estrogenic effect. Copyright © 1986 American Cancer Society