Effect of hormonal manipulation on antithrombin III activity in patients with prostatic carcinoma.

In three groups of patients with advanced prostatic cancer the influence of three different forms of hormonal manipulation, i.e. estrogens, anti-androgens and bilateral orchidectomy, on the coagulation and fibrinolytic systems has been investigated. The groups, studied over a period of 35 days, were comparable as to age and stage of malignancy. A significant decrease in antithrombin III (AT-III) activity of 27% (range 7-46%) was found in patients on an initially high-dose estrogen (diethylstilbestrol) treatment regime. No changes in any of the monitored coagulation and fibrinolytic parameters were noted in the other treatment groups, including patients on maintenance estrogen therapy. The results of this study show that only high-dose estrogen therapy is accompanied by a selective decrease in AT-III activity. This may be an important etiological factor in the increased risk of thromboembolism in patients treated by this regime. The other means of hormonal manipulation studied, including low-dose estrogen treatment, did not influence the coagulation or fibrinolytic systems.