Acceptability and patterns of endometrial bleeding in estradiol-based HRT regimens: a comparative study of cyclical sequential combinations of trimegestone or norethisterone acetate

Hormone therapy in postmenopausal women and risk of endometrial hyperplasia

BACKGROUND

Reduced circulating estrogen levels around the time of the menopause can induce unacceptable symptoms that affect the health and well-being of women. Hormone therapy (both unopposed estrogen and estrogen/progestogen combinations) is an effective treatment for these symptoms, but is associated with risk of harms. Guidelines recommend that hormone therapy be given at the lowest effective dose and treatment should be reviewed regularly. The aim of this review is to identify the minimum dose(s) of progestogen required to be added to estrogen so that the rate of endometrial hyperplasia is not increased compared to placebo.

OBJECTIVES

The objective of this review is to assess which hormone therapy regimens provide effective protection against the development of endometrial hyperplasia or carcinoma.

SEARCH METHODS

We searched the Cochrane Menstrual Disorders and Subfertility Group trials register (searched January 2012), The Cochrane Library (Issue 1, 2012), MEDLINE (1966 to January 2012), EMBASE (1980 to January 2012), Current Contents (1993 to May 2008), Biological Abstracts (1969 to 2008), Social Sciences Index (1980 to May 2008), PsycINFO (1972 to January 2012) and CINAHL (1982 to May 2008). Attempts were made to identify trials from citation lists of reviews and studies retrieved, and drug companies were contacted for unpublished data.

SELECTION CRITERIA

Randomised comparisons of unopposed estrogen therapy, combined continuous estrogen-progestogen therapy, sequential estrogen-progestogen therapy with each other or placebo, administered over a minimum period of 12 months. Incidence of endometrial hyperplasia/carcinoma assessed by a biopsy at the end of treatment was a required outcome. Data on adherence to therapy, rates of additional interventions, and withdrawals owing to adverse events were also extracted.

DATA COLLECTION AND ANALYSIS

In this update, 46 studies were included. Odds ratios (ORs) were calculated for dichotomous outcomes. The small numbers of studies in each comparison and the clinical heterogeneity precluded meta-analysis for many outcomes.

MAIN RESULTS

Unopposed estrogen is associated with increased risk of endometrial hyperplasia at all doses, and durations of therapy between one and three years. For women with a uterus the risk of endometrial hyperplasia with hormone therapy comprising low-dose estrogen continuously combined with a minimum of 1 mg norethisterone acetate (NETA) or 1.5 mg medroxyprogesterone acetate (MPA) is not significantly different from placebo at two years (1 mg NETA: OR 0.04; 95% confidence interval (CI) 0 to 2.8; 1.5 mg MPA: no hyperplasia events).

AUTHORS' CONCLUSIONS

Hormone therapy for postmenopausal women with an intact uterus should comprise both estrogen and progestogen to reduce the risk of endometrial hyperplasia.

Hormone therapy in postmenopausal women and risk of endometrial hyperplasia

BACKGROUND

Declining circulating estrogen levels around the time of the menopause can induce unacceptable symptoms that affect the health and well being of women. Hormone therapy (both unopposed estrogen and estrogen/progestogen combinations) is an effective treatment for these symptoms, but is associated with risk of harms. Guidelines recommend that hormone therapy be given at the lowest effective dose and treatment should be reviewed regularly. The aim of this review is to identify the minimum dose(s) of progestogen required to be added to estrogen so that the rate of endometrial hyperplasia is not increased compared to placebo.

OBJECTIVES

The objective of this review is to assess which hormone therapy regimens provide effective protection against the development of endometrial hyperplasia and/or carcinoma.

SEARCH STRATEGY

We searched the Cochrane Menstrual Disorders and Subfertility Group trials register (searched January 2008), The Cochrane Library (Issue 1, 2008), MEDLINE (1966 to May 2008), EMBASE (1980 to May 2008), Current Contents (1993 to May 2008), Biological Abstracts (1969 to 2008), Social Sciences Index (1980 to May 2008), PsycINFO (1972 to May 2008) and CINAHL (1982 to May 2008). Attempts were made to identify trials from citation lists of reviews and studies retrieved, and drug companies were contacted for unpublished data.

SELECTION CRITERIA

Randomised comparisons of unopposed estrogen therapy, combined continuous estrogen-progestogen therapy and/or sequential estrogen-progestogen therapy with each other or placebo, administered over a minimum period of twelve months. Incidence of endometrial hyperplasia/carcinoma assessed by a biopsy at the end of treatment was a required outcome. Data on adherence to therapy, rates of additional interventions, and withdrawals due to adverse events were also extracted.

DATA COLLECTION AND ANALYSIS

In this substantive update, forty five studies were included. Odds ratios were calculated for dichotomous outcomes. The small numbers of studies in each comparison and the clinical heterogeneity precluded meta analysis for many outcomes.

MAIN RESULTS

Unopposed estrogen is associated with increased risk of endometrial hyperplasia at all doses, and durations of therapy between one and three years. For women with a uterus the risk of endometrial hyperplasia with hormone therapy comprising low dose estrogen continuously combined with a minimum of 1 mg norethisterone acetate or 1.5 mg medroxyprogesterone acetate is not significantly different from placebo (1mg NETA: OR=0.04 (0 to 2.8); 1.5mg MPA: no hyperplasia events).

AUTHORS' CONCLUSIONS

Hormone therapy for postmenopausal women with an intact uterus should comprise both estrogen and progestogen to reduce the risk of endometrial hyperplasia.

Preclinical and clinical properties of trimegestone: a potent and selective progestin

Trimegestone (TMG) is a novel, 19-norpregnane progestin with potent and selective properties. In preclinical studies, TMG has been shown to provide high endometrial selectivity. Further, TMG has high affinity and selectivity for the progesterone receptor and lacks the agonist effects of other steroid hormones. In clinical studies, TMG has been shown to have high endometrial safety and an improved bleeding profile along with improved tolerability compared with other progestins. In addition, TMG also does not impede the beneficial effects of estrogen, especially on bone, and does not compromise quality of life. The preclinical findings of lack of mineralocorticoid activity of TMG were supported in clinical findings, with neutral effect on body weight. Similarly, the smaller effect of TMG on the GABA-ergic (gamma-aminobutyric acid) system in preclinical studies is consistent with the improvement of central nervous system-related effects on depressed mood and sleep quality in clinical studies. Low-dose estradiol/TMG regimens provide rapid relief from menopausal symptoms, reducing the number and severity of hot flushes as effectively as 2 mg 17beta-estradiol/1 mg norethisterone acetate. Therefore, it may be concluded that TMG provides a clinically proven option in hormone therapy for both clinicians and patients.

Current state of hormone replacement therapy: the case for using trimegestone

Estrogen deficiency has a negative impact on the quality of life of postmenopausal women and is associated with vasomotor symptoms, insomnia and emotional lability. Other manifestations of estrogen deficiency include dry skin, dry vagina and dyspareunia, in addition to bone loss. Estrogen replacement effectively reverses these changes. The only indication for the administration of a progestogen is to protect the postmenopausal uterus against the potential development of endometrial hyperplasia and carcinoma.

Pharmacology of estrogens and progestogens: influence of different routes of administration

This review comprises the pharmacokinetics and pharmacodynamics of natural and synthetic estrogens and progestogens used in contraception and therapy, with special consideration of hormone replacement therapy. The paper describes the mechanisms of action, the relation between structure and hormonal activity, differences in hormonal pattern and potency, peculiarities in the properties of certain steroids, tissue-specific effects, and the metabolism of the available estrogens and progestogens. The influence of the route of administration on pharmacokinetics, hormonal activity and metabolism is presented, and the effects of oral and transdermal treatment with estrogens on tissues, clinical and serum parameters are compared. The effects of oral, transdermal (patch and gel), intranasal, sublingual, buccal, vaginal, subcutaneous and intramuscular administration of estrogens, as well as of oral, vaginal, transdermal, intranasal, buccal, intramuscular and intrauterine application of progestogens are discussed. The various types of progestogens, their receptor interaction, hormonal pattern and the hormonal activity of certain metabolites are described in detail. The structural formulae, serum concentrations, binding affinities to steroid receptors and serum binding globulins, and the relative potencies of the available estrogens and progestins are presented. Differences in the tissue-specific effects of the various compounds and regimens and their potential implications with the risks and benefits of hormone replacement therapy are discussed.

Bleeding profile and endometrial safety of continuous combined regimens 1 mg 17beta-estradiol/trimegestone versus 1 or 2 mg 17beta-estradiol/norethisterone acetate in postmenopausal women

OBJECTIVE

To compare the bleeding profile and endometrial safety of continuous combined 1 mg 17beta-estradiol (17beta-E2) and 0.125 mg trimegestone (TMG) with those of two continuous combined 17beta-E2 and norethisterone acetate (NETA) regimens.

STUDY DESIGN

This was a double-blind, randomized, multicenter study conducted in 12 European countries and Israel over a 2-year period. Healthy postmenopausal women with an intact uterus were given either 1 mg 17beta-E2/0.125 mg TMG, 2 mg 17beta-E2/1 mg NETA or 1 mg 17beta-E2/0.5 mg NETA for up to 26 cycles, each of 28 days.

RESULTS

The percentage of amenorrheic women was greater in most cycles up to cycle 13 in the 1 mg 17beta-E2/0.125 mg TMG group than in the comparator groups. The mean number of bleeding days was similar in the 1 mg 17beta-E2/0.125 mg TMG and the 1 mg 17beta-E2/0.5 mg NETA groups, but greater in the 2 mg 17beta-E2/1 mg NETA group. No endometrial hyperplasia was observed for any group.

CONCLUSION

Continuous combined 1 mg 17beta-E2/0.125 mg TMG exhibits a more favorable bleeding profile than 1 mg 17beta-E2/0.5 mg NETA up to 1 year, while providing an adequate protective effect on the endometrium.

Bleeding patterns during continuous estradiol with different sequential progestogens therapy

OBJECTIVE

: To evaluate the effects on monthly bleeding of four different progestogens administered in association with transdermal estradiol in a continuous sequential estrogen-progestin therapy (CS-EPT).

DESIGN

: This prospective, open, randomized, clinical trial included 100 healthy postmenopausal women. Patients were randomized into four treatment groups, each consisting of 25 women. Treatment consisted of 50 mug/day transdermal 17beta-estradiol for all women combined to receive four different progestogens (group A: medroxyprogesterone acetate, 10 mg/day; group B: nomegestrol acetate, 5 mg/day; group C: dydrogesterone, 10 mg/day; group D: micronized progesterone, 200 mg/day) per os from the 14th to 25th day of each 28-day cycle. The duration of treatment was 12 cycles. Patients were asked to record in a daily diary the occurrence of any vaginal bleeding, the days of application of each patch, the days of assumption of the different progestogens, and the exact moment of bleeding onset.

RESULTS

: A total of 937 cycles could be evaluated. In 690 cycles (73.6%), regular progestogen-related bleeding was reported. Among the other cycles, we observed 73 episodes of amenorrhea (7.8%, each one lasting one cycle), 78 episodes of irregular bleeding (8.3%), and 96 episodes of spotting (10.2%). Patients receiving nomegestrol acetate had a significantly higher incidence of regular progestogen-associated bleeding in comparison with those receiving medroxyprogesterone acetate or natural progesterone, and patients receiving dydrogesterone had a significantly higher incidence of regular progestogen-associated bleeding in comparison with those receiving natural progesterone.

CONCLUSION

: Our data suggest that CS-EPT generally leads to regular withdrawal bleeding in women without uterine pathology. Micronized progesterone seems to induce more irregular bleeding episodes.

Role of progestins with partial antiandrogenic effects

An experts' meeting on the 'Role of progestins with partial antiandrogenic effects' was held in Berlin from January 19 to 22, 2001. The meeting was chaired by Dr R. Sitruk-Ware (New York, USA) and participants included Ms F. Fruzzetti (Pisa, Italy), J. Hanker (Trier, Germany), J. Huber (Vienna, Austria), F. Husmann (Bad Sassendorf, Germany), S. O. Skouby (Copenhagen, Denmark), J. H. H. Thijssen (Utrecht, The Netherlands), and R. Druckmann (Nice, France). The present paper reports the conclusions of the meeting. However, the publication of the Women's Health Initiative study, which appeared after the meeting, led to additional comments and revisions.

New Progestogens

The progestins have different pharmacological properties depending upon the parent molecule, usually testosterone or progesterone, from which they are derived. Very small structural changes in the parent molecule may induce considerable differences in the activity of the derivative. In postmenopausal women with an intact uterus, progestins are used in combination with estrogen as hormone-replacement therapy (HRT). The development of new generations of progestins with improved selectivity profiles has been a great challenge. Steroidal and nonsteroidal progesterone-receptor (PR) agonists have been synthesised as well, although the latter are still in a very early stage of development. Several new progestins, which have been synthesised in the last 2 decades, may be considered fourth-generation progestins. These include dienogest, drospirenone, Nestorone (Population Council, New York, NY, USA), nomegestrol acetate and trimegestone. The fourth-generation progestins have been designed to have no androgenic or estrogenic actions and to be closer in activity to the physiological hormone progesterone. Drospirenone differs from the classic progestins as it is derived from spirolactone. It is essentially an antimineralocorticoid steroid with no androgenic effect but a partial antiandrogenic effect. The antiovulatory potency of the different progestins varies. Trimegestone and Nestorone are the most potent progestins synthesised to date, followed by two of the older progestins, 3-keto-desogestrel and levonorgestrel. The new molecules trimegestone, drospirenone and dienogest also have antiandrogenic activity. Following the publication of the results of the Women's Health Initiative study, the role of progestins in HRT became controversial. Unfortunately, this concern has been directed towards progestins as a class, although striking differences exist among the progestins. Natural progesterone and some of its derivatives, such as the 19-norprogesterone molecules, and the new molecules drospirenone and dienogest are not androgenic and, therefore, have no negative effect on the lipid profile. The effects of progestins on breast tissue remain controversial as well. However, depending on the progestin and the duration of application, breast cell differentiation and apoptosis may predominate over proliferation. It is still unclear if the currently available progestins are able to bind specifically to the PR isoforms PR-A or PR-B and whether this is of clinical relevance to breast cell proliferation is also unclear. Although it is likely that the new progestins may have neutral effects on the risk of coronary heart disease or breast cancer in younger postmenopausal women, this hypothesis must be confirmed in large randomised, well controlled clinical trials.

Hormone replacement therapy: optimising the dose and route of administration

Several new products and regimens for estrogen replacement in the postmenopausal woman have recently been introduced, giving physicians and patients greater choice not only in dose but also in route of administration. Estrogen treatment in the postmenopausal woman has several proven benefits for those who have vasomotor symptoms or problems related to urogenital atrophy. However, the most controversial area is in the long-term preventive benefits of estrogen against the development of osteoporosis and cardiovascular disease, particularly in women older than 60 years. It is in these areas that decisions on the dose and optimal route of administration of estrogen replacement therapy (ERT) must be made. Although adding a progestogen to an ERT regimen is mandatory, particularly in a woman with an intact uterus, discussion now focuses on which progestogen least attenuates the beneficial effects of estrogen. Emerging trends suggest that lower doses of estrogen (i.e. ethinylestradiol 5 microg/day, estradiol 0.25 mg/day or conjugated estrogens [CEE] 0.3 mg/day) continuously combined with lower doses of medroxyprogesterone (MPA) are equally effective at relieving vasomotor symptoms as the most commonly prescribed regimen in the US (CEE 0.625mg/MPA 2.5mg daily), with fewer adverse events, leading to greater patient acceptance and likelihood for continuation of therapy. This is especially important when therapy is initiated at an older age.