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A review of selective estrogen receptor modulators in the treatment of breast and endometrial cancer.

The understanding of how estrogen affects different body tissues by selective actions on the two subtypes of estrogen receptors (alpha and beta) has created the possibility of targeted therapy by the manufacturing of a group of compounds known as selective estrogen receptor modulators. The goal of an ideal selective estrogen receptor modulator that has all the beneficial effects of estrogen receptor modulation without adverse side effects seems increasingly achievable with improving drug design. The clinical findings for the new selective estrogen receptor modulator, arzoxifene, which has been shown to be highly active in the treatment of advanced breast cancer as well as advanced endometrial cancer, has confirmed the value of selective targeting of the estrogen receptors, and may herald a new era in endocrine therapy in clinical oncology.

Antineoplastic Agents, Hormonal↗

The effects of estrogen and selective estrogen receptor modulators on cardiovascular risk factors.

Raloxifene, a selective estrogen receptor modulator, favorably alters several markers of cardiovascular risk in healthy postmenopausal women. While many of its effects are similar to those of conventional hormone replacement therapy (HRT), there are also important differences. Raloxifene lowered low-density lipoprotein cholesterol levels similarly to estrogen. However, raloxifene lacked the potentially beneficial effects of HRT on high-density lipoprotein cholesterol levels and plasminogen activation inhibitor-1, as well as the potentially adverse effects of HRT on triglycerides and C-reactive protein. Raloxifene also had a potentially beneficial fibrinogen-lowering effect not seen with conventional HRT. The net effect of these differences is unclear. Proof that raloxifene or HRT reduces the risk of heart disease must await the results of ongoing clinical trials with cardiovascular event end points.

Cardiovascular Diseases↗

Selective estrogen receptor modulators and postmenopausal women's health.

Selective estrogen receptor modulators represent an alternative approach to the use of estrogen replacement therapy or hormone replacement therapy for decreasing postmenopausal bone loss, as well as for reducing the incidence of serious cardiovascular disease in this population. Of particular interest is raloxifene, a benzothiophene compound, which binds with high affinity to the estrogen receptor and produces effects similar to estrogen on the skeleton and cardiovascular system but behaves as a complete estrogen antagonist in the uterus and the breast. The pharmacologic profile of raloxifene, a discussion of a possible mechanism of action, and the potential role of this drug in women's postmenopausal health are the subjects of this review.

Aged↗

Adverse events that are associated with the selective estrogen receptor modulator levormeloxifene in an aborted phase III osteoporosis treatment study.

OBJECTIVE: Selective estrogen receptor modulators are novel compounds that bind to the estrogen receptor and have mixed agonistic and antagonistic activities. Recently, an increase in urinary incontinence has been reported with hormone replacement therapy use. A decrease in surgical procedures for pelvic floor relaxation has been recently reported with raloxifene, a selective estrogen receptor modulator that is not uterotropic. Levormeloxifene is a selective estrogen receptor modulator that was developed for the purpose of the treatment and prevention of postmenopausal osteoporosis. STUDY DESIGN: This was a multicentered prospective study of healthy women aged >or=65 years with osteoporosis who were randomized to blindly receive placebo or levormeloxifene 0.5 mg or 1.25 mg daily as part of a planned 3-year osteoporosis treatment study. Multiple medical and gynecologic evaluations were performed. Adverse events were reported to investigators and coded with the use of World Health Organization terminology. This study was halted after 10 months because of the large number of gynecologic and other adverse events. RESULTS: Among 2924 women who were studied, those women who were treated with levormeloxifene had a marked increase compared with placebo in leukorrhea (30% vs 3%), increased endometrial thickness on ultrasound scan (19% vs 1%), enlarged uterus (17% vs 3%), uterovaginal prolapse (7% vs 2%), urinary incontinence (17% vs 4%), increased micturition frequency (9% vs 4%), lower abdominal pain (17% vs 6%), hot flushes (10% vs 3%), and leg cramps (6% vs 0.8%). All of these differences were highly statistically significant with a probability value of.0001 for each. CONCLUSION: Levormeloxifene results in multiple adverse gynecologic and other events in postmenopausal women with osteoporosis.

Abdominal Pain↗

Raloxifene: A selective estrogen receptor modulator (SERM) with multiple target system effects.

Selective estrogen receptor modulators (SERMs) exhibit a pharmacologic profile characterized by estrogen agonist activity in some tissues with estrogen antagonist activity in other tissues. These compounds were initially called "antiestrogens," but it was subsequently recognized that this inadequately described their spectrum of activities. The first widely used SERM, tamoxifen, has estrogen antagonist activity in breast tissue but shows estrogen-like activity in other tissues. Raloxifene is another SERM in clinical use, and it was developed to avoid some of the undesirable estrogen agonist actions of other SERMs to improve the drug safety profile. Raloxifene has been introduced for clinical use in treatment and prevention of postmenopausal osteoporosis. This review will explore the preclinical and clinical pharmacology of raloxifene, and compare it to other SERMs currently available for clinical use.

Bone and Bones↗

[Effect of selective estrogen receptor modulators on estrogen-sensitive tissues].

Selective estrogen receptor modulators (SERMs) act exclusively through estrogen receptors and possess tissue-specific agonistic or antagonistic properties. The effects of all referred SERMs in bone and cardiovascular system are estrogenic, namely they inhibit postmenopausal bone loss and favorably influence plasma lipoproteins and some coagulation factors. The aim of this paper is to review the effects of SERMs on estrogen-dependent breast tissues and on the endometrium. There are two types of SERMs in clinical use, based on their chemical structure: the triphenylethylenes and the benzothiophenes. The prototype of the SERMs with triphenylethylene structure is tamoxifen. Tamoxifen, like all other SERMs, is an estrogen antagonist in the breast and is widely used for adjuvant treatment of breast cancer. A recent study suggests that tamoxifen also may prevent breast cancer in patients at risk. Because of the partial estrogenic activity of tamoxifen in the endometrium, its clinical use is associated with uterine hypertrophy and an increased risk of endometrial cancer. Other triphenylethylene SERMs, droloxifene, toremifene, and idoxifene, also show efficacy in the treatment of breast cancer, in a manner similar to tamoxifen. A better toxicology profile and a decreased endometrial estrogen agonism may be advantages of the new triphenylethylene SERMs. Raloxifene is a SERM with a chemical structure different from triphenylethylenes. Raloxifene, a benzothiophene, possesses an estrogen-antagonistic effect in the breast similar to triphenylethylenes. Clinical studies on postmenopausal osteoporotic women on raloxifene as compared with placebo show a significant decrease in the rate of newly diagnosed breast cancers. In clinical studies, in contrast to tamoxifen, no stimulatory effect in the endometrium could be observed with raloxifene.

Animals↗

Selective estrogen receptor modulators: a new category of therapeutic agents for extending the health of postmenopausal women.

Selective estrogen receptor modulators are a new category of therapeutic agents that bind with high affinity to estrogen receptors and mimic the effect of estrogens in some tissues but act as estrogen antagonists in others. Tamoxifen, a triphenylethylene derivative, was the first clinically available selective estrogen receptor modulator. It is a potent antiestrogen in the breast, and its use in breast cancer patients has made it the most prescribed antineoplastic drug worldwide. It has estrogen-like activity on bone metabolism, and it also reduces cholesterol. However, its ability to produce proliferation, polyp formation, and even carcinomas in the endometrium is well known. A new selective estrogen receptor modulator, raloxifene, a benzothiopene derivative, has a clinical profile similar to that of tamoxifen. However, both preclinical and clinical studies reveal that, unlike tamoxifen, it is a pure antiestrogen in the uterus. It has recently been approved by the Food and Drug Administration for prevention of osteoporosis in postmenopausal women. This report reviews pertinent preclinical and currently available clinical studies about this new selective estrogen receptor modulator and discusses clinical applicability.

Female↗

Synthesis and pharmacology of conformationally restricted raloxifene analogues: highly potent selective estrogen receptor modulators.

The 2-arylbenzothiophene raloxifene, 1, is a selective estrogen receptor modulator (SERM) which is currently under clinical evaluation for the prevention and treatment of postmenopausal osteoporosis. In vivo structure-activity relationships and molecular modeling studies have indicated that the orientation of the basic amine-containing side chain of 1, relative to the stilbene plane, is an important discriminating factor for the maintenance of tissue selectivity. We have constructed a series of analogues of 1 in which this side chain is held in an orientation which is orthogonal to the stilbene plane, similar to the low-energy conformation predicted for raloxifene. Herein, we report on the synthesis of these compounds and on their activity in a series of in vitro and in vivo biological assays reflective of the SERM profile. In particular, we describe their ability to (1) bind the estrogen receptor, (2) antagonize estrogen-stimulated proliferation of MCF-7 cells in vitro, (3) stimulate TGF-beta3 gene expression in cell culture, (4) inhibit the uterine effects of ethynyl estradiol in immature rats, and (5) potently reduce serum cholesterol and protect against osteopenia in ovariectomized (OVX) rats without estrogen-like stimulation of uterine tissue. These data demonstrate that one of these compounds, LY357489,4, is among the most potent SERMs described to date with in vivo efficacy on bone and cholesterol metabolism in OVX rats at doses as low as 0.01 mg/kg/d.

Animals↗

Recovery of proximal tibia bone mineral density and strength, but not cancellous bone architecture, after long-term bisphosphonate or selective estrogen receptor modulator therapy in aged rats.

Various bisphosphonates and the selective estrogen receptor modulator (SERM) raloxifene are approved treatments of postmenopausal osteoporosis. They increase bone mineral density (BMD), decrease bone turnover, and reduce vertebral fracture incidence through different cellular mechanisms. We investigated the bone cellular activities, architecture, mineral content/density, and strength of ovariectomized (ovx) rats on a long-term bisphosphonate or SERM treatment, at doses of either agent correcting bone strength. Eleven weeks postovariectomy, 6-month-old rats were treated with the SERM MDL 103,323 or with the bisphosphonate pamidronate for 5 months. Doses of pamidronate and MDL 103,323 were selected from previous studies showing correction of the ovx-induced decrease of ultimate strength of proximal tibia. Ultimate and yield strengths, BMD, and histomorphometric parameters were all quantified at the same site, i.e., the proximal tibia metaphysis. Long-term pamidronate decreases bone turnover and bone formation activity, leading to trabecular thinning. MDL 103,323 decreases bone turnover to a lesser extent, and slightly protects trabecular architecture by uncoupling bone resorption and formation activities. The yield strength is corrected by pamidronate, but not by MDL 103,323 treatment. However, neither compound restores the ovariectomy-induced cancellous bone loss. Total tissue area and cortical thickness are unchanged with pamidronate or MDL 103,323 treatment, indicating that cortical bone mass, thickness, and cross-sectional area are not modified. The discrepancy between proximal tibia BMD and mechanical resistance to fracture modifications, on the one hand, and cancellous bone volume, on the other hand, could be due to changes in the degree of mineralization of bone matrix and/or of the intrinsic properties of the bone matrix.

Aging↗

Prevention and treatment of experimental breast cancer with the combination of a new selective estrogen receptor modulator, arzoxifene, and a new rexinoid, LG 100268.

The selective estrogen receptor modulator arzoxifene and the rexinoid LG 100268 were active not only as single agents for prevention and treatment of breast cancer in the rat model that uses nitrosomethylurea as the carcinogen but also showed striking synergy, both preventively and therapeutically, in a series of six experiments with a total of 465 rats. Mechanistic studies in cell culture reported here suggest that enhancement of stromal-epithelial interactions may contribute to this synergy. The possible clinical use of the combination of arzoxifene and LG 100268 for prevention of breast cancer in women at high risk, for treatment of women in the adjuvant setting, or for treatment of end-stage disease should now be considered.

Animals↗

Endothelial protective and antishock effects of a selective estrogen receptor modulator in rats.

This study investigated whether idoxifene, a selective estrogen receptor modulator (SERM), exerted protective effects against ischemia-reperfusion-induced shock. Ovariectomized rats were treated with vehicle, idoxifene, or 17beta-estradiol for 4 days. Rats were subjected to splanchnic artery occlusion (SAO) followed by reperfusion (SOA/R). In vehicle-treated rats, SAO/R resulted in hypotension, hemoconcentration, increased plasma tumor necrosis factor (TNF)-alpha levels, intestinal neutrophil accumulation, and endothelial dysfunction. 17beta-Estradiol treatment increased plasma estradiol concentration and reduced SAO/R-induced tissue injury. Idoxifene treatment had no effect on plasma estradiol concentration but reduced SAO/R-induced hemoconcentration (+8.8 +/- 1.3 vs. +14 +/- 1.3% in the vehicle group, P < 0.01), TNF-alpha production (98 +/- 3.2 vs. 214 +/- 13 pg/ml, P < 0.01), and neutrophil accumulation (0.025 +/- 0.005 vs. 0.047 +/- 0.005 U/g protein, P < 0.01). It also improved endothelial function, prolonged survival time (172 +/- 3.5 vs. 147 +/- 8 min, P < 0.01), and increased survival rate (69 vs. 23%, P < 0.01). Moreover, treatment with 17beta-estradiol or idoxifene in vivo reduced TNF-alpha-induced endothelial dysfunction in vitro. Taken together, these results demonstrated that idoxifene exerted estrogen-like, endothelial-protective, and antishock effects in ovariectomized rats, suggesting that SERMs have therapeutic potential in tissue injury resulting from ischemia-reperfusion.

Animals↗

Proliferative lesions of ovarian granulosa cells and reversible hormonal changes induced in rats by a selective estrogen receptor modulator.

This study assessed the effects of raloxifene, a selective estrogen receptor modulator (SERM), on ovarian morphology and circulating hormone levels in rats. Female Fischer-344 rats (65/group) were given dietary raloxifene for 6 months at average daily doses of 0, 15, 75, and 365 mg/kg. Morphologic evaluation of ovaries was conducted on 25 rats/group at the end of the treatment period and from 20 rats per group after 1 and 3 months withdrawal from treatment. Plasma hormone analyses were conducted on 10 rats pergroup at the end of the treatment period and aftereach withdrawal period. Treatment with raloxifene for 6 months resulted in disruption of the hypothalamic-pituitary-ovarian axis, manifested by increased plasma concentrations of luteinizing hormone (LH) and estradiol-17beta (E2), and failure of ovulation, manifested by ovarian follicular prominence (retained anovulatory follicles), lack of corpora lutea (CL), and depressed plasma progesterone (P4). Many (56% to 80%) rats in all raloxifene treated groups had focal, minimal to slight hyperplasia of granulosa cells within individual retained follicles. A few treated rats in the mid- and high-dose groups (2 of 25 and 3 of 25, respectively) had more extensive focal proliferation of granulosa cells. These foci were approximately 3 to 6 mm in overall size and were characterized by moderate papillary proliferation of large granulosa cells associated with cystic spaces, often with hemorrhage. In 4 of the 5 rats with this focal cystic granulosa cell hyperplasia, the remainder of the involved ovary and the contralateral ovary were atrophic. After 1 or 3 months of drug withdrawal, most previously treated rats examined had morphologic evidence of ovarian cyclic changes. including developing follicles, various stages of CL, and normal plasma levels of LH, E2, and P4. Continued lack of cyclic changes was limited to 4 of 20 rats from the low-dose group after 1 month of recovery and to 1 low dose rat after 3 months. Intrafollicular granulosa cell hyperplasia was not seen in rats in the reversibility phase. Areas of prior focal cystic granulosa cell hyperplasia were represented by focal sclerosis that included hemorrhage and/or hemosiderin. The foci of sclerosis were associated with cystic spaces after 1 month and were solid after 3 months. A granulosa cell tumor, approximately 12-13 mm diameter, was present in a high-dose rat in the 3-month reversibility group. This tumor effaced 1 ovary and was characterized by proliferative granulosa cells, usually in papillary formations and cords within cystic spaces. This rat had atrophy of the uninvolved ovary, excessive plasma levels of E2 and prolactin, and high P4 levels considering the absence of CL. The results of this study indicate that ovarian granulosa cells in rats are susceptible to proliferative changes when stimulated chronically with excessive trophic hormones. Most of these proliferative changes were reversible upon cessation of the hormonal stimulation. However, the proliferative lesion in one treated rat progressed to apparent autonomous (neoplastic) growth.

Animals↗

Proliferative lesions of ovarian granulosa cells and reversible hormonal changes induced in rats by a selective estrogen receptor modulator.

This study assessed the effects of raloxifene. a selective estrogen receptor modulator (SERM), on ovarian morphology and circulating hormone levels in rats. Female Fischer-344 rats (65/group) were given dietary raloxifene for 6 months at average daily doses of 0, 15, 75, and 365 mg/kg. Morphologic evaluation of ovaries was conducted on 25 rats/group at the end of the treatment period and from 20 rats per group after 1 and 3 months withdrawal from treatment. Plasma hormone analyses were conducted on 10 rats per group at the end of the treatment period and after each withdrawal period. Treatment with raloxifene for 6 months resulted in disruption of the hypothalamic-pituitary-ovarian axis, manifested by increased plasma concentrations of luteinizing hormone (LH) and estradiol-17beta (E2), and failure of ovulation, manifested by ovarian follicular prominence (retained anovulatory follicles), lack of corpora lutea (CL), and depressed plasma progesterone (P4). Many (56% to 80%) rats in all raloxifene treated groups had focal, minimal to slight hyperplasia of granulosa cells within individual retained follicles. A few treated rats in the mid- and high-dose groups (2 of 25 and 3 of 25, respectively) had more extensive focal proliferation of granulosa cells. These foci were approximately 3 to 6 mm in overall size and were characterized by moderate papillary proliferation of large granulosa cells associated with cystic spaces, often with hemorrhage. In 4 of the 5 rats with this focal cystic granulosa cell hyperplasia, the remainder of the involved ovary and the contralateral ovary were atrophic. After 1 or 3 months of drug withdrawal, most previously treated rats examined had morphologic evidence of ovarian cyclic changes, including developing follicles, various stages of CL, and normal plasma levels of LH, E2, and P4. Continued lack of cyclic changes was limited to 4 of 20 rats from the low-dose group after 1 month of recovery and to 1 low dose rat after 3 months. Intrafollicular granulosa cell hyperplasia was not seen in rats in the reversibility phase. Areas of prior focal cystic granulosa cell hyperplasia were represented by focal sclerosis that included hemorrhage and/or hemosiderin. The foci of sclerosis were associated with cystic spaces after 1 month and were solid after 3 months. A granulosa cell tumor, approximately 12-13 mm diameter, was present in a high-dose rat in the 3-month reversibility group. This tumor effaced 1 ovary and was characterized by proliferative granulosa cells, usually in papillary formations and cords within cystic spaces. This rat had atrophy of the uninvolved ovary, excessive plasma levels of E2 and prolactin, and high P4 levels considering the absence of CL. The results of this study indicate that ovarian granulosa cells in rats are susceptible to proliferative changes when stimulated chronically with excessive trophic hormones. Most of these proliferative changes were reversible upon cessation of the hormonal stimulation. However, the proliferative lesion in one treated rat progressed to apparent autonomous (neoplastic) growth.

Animals↗

Chemoprevention of breast cancer with selective estrogen receptor modulators: views from broadly diverse focus groups of women with elevated risk for breast cancer.

Selective estrogen receptor modulators (SERMs) are anti-estrogens that selectively antagonize the proliferative effects of estrogens on breast cells, thereby inhibiting or reversing neoplastic progression to clinical breast cancer. The goal is to administer these agents to healthy women with an elevated risk for breast cancer. The study reported here assessed the knowledge and attitude of 26 broadly selected women with an elevated risk for breast cancer who participated in three focus groups (eight to ten per group) that discussed the use of SERMs, such as tamoxifen and raloxifen. Data were analyzed by cross-case procedure using variable-oriented strategies. Acceptance of breast cancer chemoprevention treatment with SERMs was found to be influenced by various factors, including a knowledge of breast cancer risk factors, the perception of personal risk for breast cancer, and the perception of barriers and benefits to receiving chemoprevention treatment. The issues involved in making the decision to accept treatment with SERMs are discussed. Most of the participants in the groups indicated they were unlikely to accept breast cancer chemoprevention treatment with SERMs.

Adult↗

Differential effects of selective estrogen receptor modulators and estrogens on mammary blood flow in the ovine.

OBJECTIVE: Hormone replacement therapy has been implicated in the increased incidence of breast cancer, although selective estrogen receptor modulators have been shown to be effective in the prevention of breast cancer. Breast cancers are associated with increased mammary blood flow compared to benign breast lesions. However, few studies have examined the hemodynamic effects of hormonal agents on the mammary circulation that promote or reduce the risk of breast cancers. Although estradiol-17beta has been shown to increase mammary blood flow, the effect of selective estrogen receptor modulators remains undetermined. We therefore compared the vascular effects of selective estrogen receptor modulators and estrogens on mammary blood flow. STUDY DESIGN: Fourteen nonpregnant ovariectomized ewes were instrumented to measure mean arterial pressure, heart rate, and uterine and mammary blood flows. Compounds were administered intravenously on separate days, and responses were monitored up to 4 hours. Compounds that were studied included estradiol-17beta (1 microg/kg), conjugated equine estrogens (0.625 and 1.25 mg), tibolone (2.5 and 5 mg), raloxifene (10 microg/kg), and tamoxifen (300 microg/kg). RESULTS: None of these compounds significantly affected mean arterial pressure or heart rate, but all of the compounds significantly increased uterine blood flow. Estradiol-17beta increased mammary blood flow by 98% +/- 25%; conjugated equine estrogen increased mammary blood flow by 46% +/- 6% and 68% +/- 13% at the 0.625 and 1.25 mg doses, respectively. Tibolone increased mammary blood flow by 37% +/- 13% at the 2.5-mg dose and by only 14% +/- 4% at the 5-mg dose. Neither raloxifene nor tamoxifen significantly altered mammary blood flow. CONCLUSION: Although estrogens and selective estrogen receptor modulators induced similar increases in uterine blood flow, they had differential effects on mammary blood flow.

Animals↗

Selective estrogen receptor modulators: mechanism of action and clinical experience. Focus on raloxifene.

Selective estrogen receptor modulators (SERMs) are a diverse group of compounds that bind with specific, high-affinity binding to the estrogen receptor (ER). Depending on the tissue, SERMs can act as either ER agonists or antagonists. Recent advances in ER biology have provided insight into possible mechanisms by which SERMs elicit these tissue-specific estrogen agonist and estrogen antagonist activities. The estrogen response pathway has been shown to differ among target tissues depending on various tissue and cellular factors, such as the ER subtype, the structure of the bound receptor-ligand complex, and the tissue-specific cellular transcriptional machinery. Clinically available SERMs include clomiphene, tamoxifen and toremifene, which are triphenylethylenes, and raloxifene, a benzothiophene. Raloxifene has estrogen agonist effects on bone, serum lipids, and arterial vasculature, and estrogen antagonist effects in breast and uterus. Clinical trial data for raloxifene is used to illustrate some of the mechanisms by which SERMs exert their tissue-specific estrogen agonist and estrogen antagonist effects. The complex pharmacology surrounding the tissue selectivity of SERMs is discussed.

Clinical Trials as Topic↗

Comparative tolerability of first-generation selective estrogen receptor modulators in breast cancer treatment and prevention.

In general, the selective estrogen receptor modulators (SERMs) currently indicated for the treatment and prevention of breast cancer, i.e. tamoxifen and toremifene, are fairly well tolerated. However, tamoxifen has been shown to induce hepatocellular carcinomas in rats, but not in humans, and can increase the risk of endometrial cancer in humans by two to three times. Other potentially serious adverse effects which have been associated with tamoxifen and toremifene therapy include vasomotor symptoms, an increased risk of venous thromboembolic events, and an increased incidence of cataracts and ocular toxicity, fatty liver, and nonmalignant hepatic and uterine changes. In addition, long term tamoxifen use almost always results in resistance to the drug and, indeed, has actually been shown to promote tumour proliferation in human breast cancer cells. Both tamoxifen and toremifene display drug interactions with a variety of drug classes. The adverse events associated with these compounds have raised significant concerns regarding their widespread use for the treatment and prevention of breast cancer. In addition, because of the weakness and scarcity of the data on toremifene, any conclusions about its tolerability remain tentative until outcomes of ongoing clinical trials in the adjuvant setting are known. A third SERM, raloxifene, is the focus of several large randomised trials examining its efficacy in the prevention of breast cancer. At present, each potential adverse event needs to be weighed against potential benefits in the decision to undergo SERM treatment. An array of therapies is currently available for patients with breast cancer and women at increased risk of disease; the risk-to-benefit ratio for each agent should be carefully examined in determining the most advantageous regimen.

Animals↗

Selective estrogen receptor modulation and reduction in risk of breast cancer, osteoporosis, and coronary heart disease.

The recognition of selective estrogen receptor modulation in the laboratory has resulted in the development of two selective estrogen receptor modulators (SERMs), tamoxifen and raloxifene, for clinical application in healthy women. SERMs are antiestrogenic in the breast but estrogen-like in the bones and reduce circulating cholesterol levels. SERMs also have different degrees of estrogenicity in the uterus. Tamoxifen is used specifically to reduce the incidence of breast cancer in premenopausal and postmenopausal women at risk for the disease. In contrast, raloxifene is used specifically to reduce the risk of osteoporosis in postmenopausal women at high risk for osteoporosis. The study of tamoxifen and raloxifene (STAR) trial is currently comparing the ability of these SERMs to reduce breast cancer incidence in high-risk postmenopausal women. There is intense interest in understanding the molecular mechanism(s) of action of SERMs at target sites in a woman's body. An understanding of the targeted actions of this novel drug group will potentially result in the introduction of new multifunctional medicines with applications as preventive agents or treatments of breast cancer and endometrial cancer, coronary heart disease, and osteoporosis.

Adult↗