Inhibition of platelet aggregation caused by estrogen treatment in patients with carcinoma of the prostate

Abstract

Platelet aggregation is increased in patients with carcinoma of the prostate treated with estrogens. Hence, these patients have a high incidence of cardiovascular and thromboembolic diseases. Platelet aggregation has been tested with the platelet aggregation test. It was inhibited by administration of 500 mg. acetylsalicylic acid twice daily. An aggregation inhibiting effect has been found in all 38 patients. To reduce the excess hazards of cardiovascular complications of estrogens in treating carcinoma of the prostate acetylsalicylic acid is recommended as an adjunct therapy.

PIP: Estrogen therapy for prostatic carcinoma may lead to the development of cardiovascular complications, such as thrombosis. Platelets play a role in the development of thrombosis. This study examines platelet function before and during estrogen treatment in 83 patients with histologically proven prostatic carcinoma undergoing long-term estrogen therapy. Platelet aggregation was tested at least 5 times/month. Statistical tests were done on 56 patients divided into 3 groups: 1) 14 patients without estrogen treatment; 2) 33 patients during estrogen therapy; and 3) 9 patients considered an increased risk (myocardial infarction, status after thromboembolization) who did not receive estrogen. 38 patients with prostatic carcinoma were similarly evaluated in another test series, each patient initially receiving 9.2 gm stilbestrol diphophate infusions and subsequently 80 mg polyestradiol phosphate intramuscularly and 0.2 mg ethinyl estradiol orally every day. Increased tendency for thrombocyte aggregation was inhibited in these patients by oral administration twice daily of 500 mg acetylsalicilic acid. This regimen in addition to the hormone therapy was continued for a minimal period of 3 months. Group 3 exhibited the worse platelet aggregation test of all the groups. Acetylsalicilic acid therapy significantly reduced aggregation in the stilbestrol diphosphate as well as polyestradiol phosphate treatment groups (p0.005). None of the patients treated with acetylsalicilic acid for 4 to 7 months had thrombosis or cardiovascular complications, although in 10 patients this therapy had to be discontinued because of recurrent gastric disturbances. It is recommended that patients with prostatic carcinoma on estrogen therapy be given an adjunct dose of 1 gm acetylsalicilic acid daily. The inhibitory effect on platelet aggregation of acetylsalicilic acid is discussed.