ADJUVANT ANTIESTROGEN TREATMENT WITH TAMOXIFEN IN POSTMENOPAUSAL WOMEN WITH BREAST-CANCER - A LONGITUDINAL-STUDY OF BLOOD-COAGULATION AND FIBRINOLYSIS

Potential effects of tamoxifen therapy on blood coagulation and fibrin olysis were investigated in women with breast cancer. We studied 14 pa rameters of hemostasis in 19 postmenopausal women receiving 20 mg tamo xifen/day as an adjuvant treatment. Blood sampling was done before and after the 1st, 3rd, and 6th month of treatment. Pretreatment values o f procoagulation, anticoagulation, plasminogen, and plasminogen activa tor inhibitor were found within the reference range, whereas tissue-pl asminogen activator, fibrin degradation products, and prothrombin-frag ment 1+2 were elevated. On therapy an initial decrease of all measured parameters was observed. The effect was pronounced in coagulation inh ibitors (antithrombin III, protein C and S), No pathological values (b elow 60%) were observed. No further effects were found during the 3rd and 6th month of treatment. Our data indicate that the decrease of hem ostatic parameters during the initial phase of tamoxifen treatment is due to the timing of blood collection, which took place no more than 1 4 days after surgery. The reduction of coagulation inhibitors was not associated with pathological values. No cumulative effects were seen d uring tamoxifen therapy. The decrease was not associated with a concom ittant increase of in vivo coagulation markers (prothrombin-fragment 1 +2, thrombin-antithrombin-complex, fibrin degradation products). There fore our results are likely to reflect only the resolution of postoper ative activation and do not translate into a drug related thrombogenic effect.