Effect of transdermal oestradiol on the haemostatic balance of menopausal women

TRANSDERMAL ESTRADIOL THERAPY FOR PROSTATE CANCER REDUCES THROMBOPHILIC ACTIVATION AND PROTECTS AGAINST THROMBOEMBOLISM

PURPOSE

Oral estrogens were an effective treatment for prostate cancer but were abandoned because of an increased risk of cardiovascular toxicity and particularly thromboembolism. We have recently shown that transdermal estradiol produces an effective tumor response and negligible cardiovascular toxicity. Here we report the influence of transdermal estradiol therapy on the coagulation profile of men with advanced prostate cancer.

MATERIALS AND METHODS

A total of 20 patients with newly diagnosed locally advanced or metastatic prostate cancer were treated using transdermal estradiol patches and the coagulation profile was assessed before and during 12 months therapy. Activation of coagulation was assessed by assaying the levels of activated factor VII (VIIa), activated factor XII (XIIa), prothrombin fragments 1 and 2 (F1 + 2), thrombin-antithrombin III (TAT III) complex and fibrinogen. Inhibition of the coagulation cascade was assayed by protein C, protein S and activated protein C resistance (APC-R). Fibrinolytic activity was determined by assaying tissue plasminogen activator (TPA) and plasminogen activation inhibitor type 1 (PAI-1). D-Dimer levels assessed both coagulation and fibrinolytic (thrombophilic) activity. Venous Duplex, color Doppler ultrasound and photoplethysmography were used to assess for thrombosis.

RESULTS

Levels of VIIa and XIIa were unaffected by transdermal estradiol therapy. Although levels of TAT III were increased in some patients at 12 months, the increase was markedly less than that observed historically with equivalent doses of oral estrogens. Levels of the inhibitory and fibrinolytic factors including protein C, protein S, APC-R, TPA and PAI-1 remained stable. Reductions in F1+F2, fibrinogen and D-Dimer levels represented a normalization from increased levels to the physiological range.

CONCLUSIONS

These results suggest that transdermal estradiol reduces thrombophilic activation in men with advanced prostate cancer, and protects against the risk of thrombosis.

Hormone replacement therapy and cardiovascular disease: increased risks of venous thromboembolism and stroke, and no protection from coronary heart disease

Hormone replacement therapy (HRT) was increasingly promoted over the last 40 years to improve quality of life, and to reduce the risks of osteoporotic fractures and coronary heart disease (CHD). In recent years, observational studies, randomized trials and systematic reviews of such trials have shown that HRT does not reduce, but actually increases cardiovascular risk. HRT increases the relative risks of venous thromboembolism (twofold), and of fatal or disabling stroke (by 50%); whilst increasing the early risk of myocardial infarction and having no protective effect against CHD on longer term use. Possible mechanisms for these increased cardiovascular risks include down-regulation of several inhibitory pathways of blood coagulation, resulting in increased coagulation activation, which promotes venous and arterial thrombosis. The implications for prescription are discussed, as are lessons for future evaluation of health care interventions.

Hemostatic Factors and Ischemic Heart Disease Risk Among Postmenopausal Women

The following is a review of (largely) epidemiologic evidence on whether changes in plasma hemostatic concentrations occur with menopause and with postmenopausal hormone therapy which may have an impact on risk of ischemic heart disease. To date, only plasma fibrinogen has been positively associated with long-term risk of disease among women; however, data are sparse. Taken together, the evidence supports an impact of endogenous sex hormone levels on thrombotic potential and points to a modest increase in a number of plasma hemostatic factor levels at menopause. Results of studies of estrogen therapy are somewhat conflicting. Observational findings suggest that, except for possibly the Factor VII level, estrogen therapy may prevent the menopause-related rise in plasma hemostatic factors. In contrast, controlled experiments have found increased markers of thrombin generation with use of common formulations of estrogen therapy. The hemostatic effects found with oral preparations do not appear to occur with transdermal forms of estrogen although data are limited. Overall, the evidence shows menopause to have an impact on plasma levels of hemostatic factors which appears to be modified by use of oral estrogen. Whether these alterations in plasma levels have an impact on risk of ischemic heart disease among postmenopausal women remains to be demonstrated.

Maximising the use of HRT: focus on hysterectomised women

Hysterectomy is one of the most common gynaecological surgical operations performed in the UK. In addition to causing the early onset of the menopause, hysterectomy can lead some women to be at increased risk of future CHD and osteoporosis owing to declining oestrogen levels. Hysterectomised women are therefore an ideal group to receive hormone replacement therapy (HRT). However, only small numbers of women receive HRT owing to a number of factors, including fear of potential complications and adverse side-effects. Of those women who do receive HRT, compliance with therapy is low. In this article, the authors weigh the benefits of HRT, in terms of relief of menopausal symptoms, and prevention of osteoporosis, Alzheimer's disease and cardiovascular disease, against the known risks. The authors suggest that compliance with HRT could be optimised by profiling patients in general practice and by educating women on the long-term benefits of HRT.

Various actions of oestrogens on the vascular system

Epidemiological studies show a reduction in cardiovascular disease with postmenopausal oestrogen use. Oestrogens have been shown to have both metabolic effects and direct effects on the vasculature, both of which may improve arterial function and reduce or reverse atheroma formation. The metabolic effects include changes in lipids and lipoproteins, glucose and insulin metabolism, coagulation and fibrinolysis. The direct arterial effects include changes in endothelium-dependent processes, ion channels, renin-angiotensin system and remodelling processes. The various actions of oestrogens on the vascular system are reviewed. It is clearly important to understand the biological basis of these effects of oestrogen on the cardiovascular system in order to optimize current and future hormone-replacement therapy in women after natural or surgical menopause.

Oral contraceptives and hormone replacement therapy do not increase the incidence of arterial thrombosis in a nonhuman primate model

Older oral contraceptive (OC) formulations containing high doses of potent synthetic estrogens and progestins are associated with increased risk of thrombosis. To examine the effects of current low-dose OC and hormone replacement therapy (HRT) regimens on arterial thrombosis, premenopausal and surgically postmenopausal cynomolgus monkeys were divided into four treatment groups. Premenopausal monkeys were given either no OCs or ethinyl estradiol and levonorgestrel as an OC at a dose equivalent to that currently given to women. Postmenopausal monkeys were given either no HRT or conjugated equine estrogens and medroxyprogesterone as an HRT at a dose equivalent to that currently given to women. The monkeys were fed an atherogenic diet containing these treatments for 27 to 30 months. At the end of this time, arterial thrombosis was evaluated with a standardized stenosis/injury procedure in the left carotid artery. Blood flow velocity was monitored for cyclic or permanent occlusive thrombosis. The current OC and HRT regimens did not increase the susceptibility of the artery wall to develop an occlusive thrombus following injury and stenosis. In fact, there was a reduction in the incidence of thrombosis in the OC animals compared with untreated controls. Increased amounts of atherosclerosis were associated with an increased incidence of occlusive arterial thrombosis. Several selected coagulation parameters [von Willebrand factor, protein C, lipoprotein(a), and platelet aggregation] did not appear to be associated with either the amount of atherosclerosis or incidence of arterial thrombosis.

Venous thrombo-embolism and hormone replacement therapy

Recent data have indicated that hormone replacement therapy (HRT) is associated with an increased risk of venous thrombo-embolism. Although the relative risk is significantly higher, the absolute risk remains small. Epidemiological studies on which the increased risk was based may have been open to biases, including those of referral, investigation and diagnosis. None the less, the association appears real albeit the mechanism poorly understood. Potential mechanisms include unmasking of an underlying thrombophilia or combination with other recognized risk factors for venous thrombo-embolism. The implications of these findings have to be placed firmly in the clinical context and weighed against the established benefits of hormone replacement therapy, including relief of menopausal symptoms, prevention of osteoporosis and arterial-vascular disease. Patients with a personal or family history of venous thrombo-embolism should be screened for underlying thrombophilia and such screening may be extended to relatives. However, the risk of venous thrombo-embolism following initiation of HRT is not yet known. None the less, HRT should be used with caution in this situation and may be best avoided, unless associated with concomitant antithrombotic therapy, in certain thrombophilias, expert advice should be sought. Patients without risk factors should be advised of the small increase in risk of venous thrombosis which is greatest during the first year. Where additional risk factors are present the situation will have to be assessed on an individual basis for each patient. For example, the beneficial effects of HRT in an obese patient at risk of arterial disease may outweigh the small risk of thrombosis. Patients already on HRT should have some assessment of the risk of venous thrombosis made and where there are features suggestive of thrombophilia screening performed.

Effects of estrogen replacement therapy on thrombin generation

The aim of this study was to investigate the hemostatic system in menopausal women before and after three months of treatment with transdermal estradiol (TTS 50, 50 micrograms/die, n = 13) or coniugated equine estrogen (CEE, 0.625 mg/die, n = 9) by evaluating : beta-thromboglobulin, platelet factor 4, factor VIIag, factor VIIc, fibrinopeptide A-FPA-, thrombin-antithrombin-TAT-complexes, antithrombin-AT-activity, protein C, plasma fibrinolytic activity (euglobulin clot lysis time), plasminogen and antiplasmin activity. FPA levels significantly increased during TTS 50 treatment (p < 0.001) while protein C showed a slight but significant decrease in both treatments (TTS 50 p < 0.001, CEE p < 0.05). TAT complexes and AT were found unaltered. Platelet function and fibrinolytic activity did not significantly change. A significant relationship between FPA and estradiol levels, which were significantly increased during. TTS 50 therapy, was found (r = 0.40, p < 0.05). These findings indicate that unopposed estradiol given by transdermal route induces a slight but significant blood clotting activation, which seems strictly related to its biological activity.

Metabolic effects of the menopause and oestrogen replacement

There is little doubt that the metabolic disturbances seen following the loss of ovarian function are most important in the development of cardiovascular disease in women. The loss of hormones at the menopause appears to reduce both insulin secretion and elimination, but increasing insulin resistance thereafter brings about an increase in circulating insulin concentrations. Changes in lipids and lipoproteins are in an adverse direction, as are changes in body fat distribution, and changes in haemostatic factors would tend to favour coagulation rather than fibrinolysis. HRT with oestrogen appears to improve most of the metabolic abnormalities related to the menopause, but this is in part dependent on the type of oestrogen used and the route of administration. The addition of progestogen may influence the metabolic changes induced by oestrogens, and this will vary according to the type of the progestogen. Overall, the metabolic effects of any of the current HRT regimens would seem likely to be beneficial for CHD. Nevertheless, future HRT regimens should ideally be tailored to produce the most favourable changes in CHD metabolic risk factors, particularly in the case of the regimens which attempt to avoid cyclical bleeding.

Transdermal estrogen replacement therapy: beneficial effects on hemostatic risk factors for cardiovascular disease

OBJECTIVES

To assess the effect of estrogen replacement therapy on hemostatic risk factors for cardiovascular disease (CVD) in postmenopausal women during 2 years of treatment.

METHODS

In an open prospective study, patients (n = 42) were investigated before and during 2 years of treatment, and compared to an untreated postmenopausal control group (n = 18) followed during the same period, healthy premenopausal women (n = 20) being included as a reference group for premenopausal values. The patients underwent treatment with transdermal 17 beta-estradiol (E2) (50 micrograms/24 h), oral medroxyprogesterone acetate (5 mg/day) being added for 12 days every second month.

RESULTS

After 2 years of treatment there was a significant increase in t-PA antigen (P = 0.01) and a significant decrease in F VII antigen (P = 0.01). PAI-1 antigen concentrations decreased slightly. Fibrinogen concentrations were already significantly decreased at 3-month follow-up (P = 0.01), and were still low after 2 years. By contrast, at 2-year follow-up the postmenopausal control group manifested significant increases in F VII and PAI-1 antigen and slight increases in fibrinogen, which resulted in significant differences between patients and controls. Regression analysis showed the increase in the serum estradiol concentrations to be inversely correlated to the decreases in the plasma concentrations of F VII antigen (r = -0.34, P = 0.001) and fibrinogen (r = -0.35, P = 0.001). There were no changes in AT III or protein C in any group.

CONCLUSIONS

The increase in serum estradiol concentrations due to replacement therapy did not adversely affect the studied components of the fibrinolytic and protein C defense system against thrombosis, and resulted in beneficial decreases in F VII antigen and fibrinogen. These findings may help to explain the beneficial effects of estrogen replacement therapy in terms of protection from cardiovascular disease.

The menopause and hormone replacement therapy: lipids, lipoproteins, coagulation and fibrinolytic factors

OBJECTIVES

To review the recent literature concerning the effects of the menopause and hormone replacement therapy (HRT) on the plasma lipoprotein and hemostatic system, as well as on the interaction between these two coronary heart disease (CHD) risk factor systems. METHODS. Collection of information from relevant scientific journals, and by the use of Medline and Current Contents.

RESULTS

The mainly beneficial effects of unopposed oral estrogen replacement on the plasma lipoprotein pattern are preserved to different degrees after addition of progestin to the regimen. Nortestostorone-derived progestins tend to lower HDL cholesterol levels more than progesterone derivatives. The slight triglyceride-elevating effect on conjugated equine estrogens was in a large study not significantly counteracted by progesterone derivatives but can, according to other studies, be reversed by nortestosterone-derived progestins. A limited number of studies on transdermal administration of estradiol has suggested that the effects on plasma lipoproteins are smaller than during oral administration. There is no convincing evidence that currently used HRT regimens would significantly increase the risk of thrombosis. Nevertheless, the finding in some studies that plasma triglyceride elevations could in theory be associated with impaired fibrinolysis and enhanced coagulation merit further attention as some HRT regimens tend to increase plasma triglyceride levels. From a theoretical point of view, transdermal estrogen delivery would be preferable in women at risk for thrombosis, as they have less pronounced effects on liver functions, including production of hemostatic factors and very-low-density lipoprotein triglycerides.

CONCLUSIONS

While the numerous existing HRT regimens provide many alternative and useful possibilities, further studies are needed concerning (a) novel progestins with minimal HDL cholesterol lowering effects, (b) transdermal and other non-oral routes for HRT, (c) possible antioxidative properties of estrogen and (d) metabolic links between the lipoprotein and hemostatic risk factor systems.