Breast cancer and hormone-replacement therapy: the Million Women Study.
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Breast Neoplasms↗
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Treatment of menopausal symptoms: what shall we do now?
During the past few years, many women and doctors have revised their opinions of hormone replacement therapy (HRT) for menopausal symptoms, and a substantial number of individuals have discontinued its use because of concerns about side-effects. Numerous alternatives to HRT are promoted, and assessment of the quality of evidence about the safety and effectiveness of these compounds can be difficult. In this Review, we summarise the data from studies addressing the efficacy, risks, and benefits of frequently prescribed treatments, and offer evidence-based clinical guidelines for the management of menopausal symptoms. Although few comparative studies exist, oestrogen alone or combinations of oestrogen and progestagen are likely to be the most effective treatments for menopausal hot flushes and vaginal dryness. Tibolone is as effective as HRT, however, and might also improve libido. For those who wish to avoid hormonal treatments, there are few effective options. Selective serotonin reuptake inhibitors might be effective in the very short term (less than 12 weeks) and are well tolerated. There is not enough evidence that any of the complementary therapies available are any better than placebo for menopausal vasomotor symptoms, and few safety data exist.
Breast Neoplasms↗
Dietary agents in cancer prevention: flavonoids and isoflavonoids.
Flavones and isoflavones may play a prominent role in cancer prevention since these compounds are found in numerous plants that are associated with reduced cancer rates. This article reviews recent epidemiological and animal data on isoflavones and flavones and their role in cancer prevention. It covers aspects of the bioavailability of these dietary constituents and explores their mechanism of action. Human epidemiology data comes primarily from studies in which foods rich in isoflavones or flavones are associated with cancer rates. This approach has been particularly useful with isoflavones because of their abundance in specific foods, including soy foods. The bioavailability of flavones and isoflavones has been shown to be influenced by their chemical form in foods (generally glycoside conjugates), their hydrophobicity, susceptibility to degradation, the microbial flora of the consumer, and the food matrix. Some information is available on how these factors influence isoflavone bioavailability, but the information on flavones is more limited. Many mechanisms of action have been identified for isoflavone/flavone prevention of cancer, including estrogenic/antiestrogenic activity, antiproliferation, induction of cell-cycle arrest and apoptosis, prevention of oxidation, induction of detoxification enzymes, regulation of the host immune system, and changes in cellular signaling. It is expected that some combination of these mechanisms will be found to be responsible for cancer prevention by these compounds. Compelling data suggest that flavones and isoflavones contribute to cancer prevention; however, further investigations will be required to clarify the nature of the impact and interactions between these bioactive constituents and other dietary components.
Animals↗
Quinoids, quinoid radicals, and phenoxyl radicals formed from estrogens and antiestrogens.
Estrogens have a variety of beneficial effects in vivo including protection against osteoporosis, coronary heart disease, Alzheimer's disease, and stroke. Similarly, antiestrogens have been shown to be effective both in treating breast cancer as well as preventing this disease. Despite the health benefits of these drugs adverse side effects have been reported including increased risk for developing certain hormone dependent cancers. Although an estrogenic mechanism likely contributes to mechanism of estrogen/antiestrogen carcinogenesis there is substantial evidence to suggest that metabolism to reactive intermediates is also involved. Both estrogens and antiestrogens can be metabolized to phenoxyl radicals, o-quinones, and semiquinone radicals, all of which could cause damage in cells either through alkylation or oxidation of cellular macromolecules including DNA. In contrast, there are several reports that estrogens and antiestrogens can act as antioxidants which could protect cells against free radical mediated damage and contribute to the beneficial effects of these compounds discussed above. The focus of this review is the role of quinoids, quinoid radicals, and phenoxyl radicals in the biological effects of estrogens and antiestrogens.
Animals↗
Modeling of signaling pathways for endocrine disruptors.
The so called endocrine disruptors have become an important working hypothesis for a wide range of toxicology researchers. This hypothesis has also attracted those who have worked on designer estrogens or selective estrogen receptor modulators. Already numbers of substances have been identified as such chemicals, but there remain a large number of chemicals waiting to be tested for their endocrine modulating capabilities. Because of the time and costs required for wet lab tests, it is unrealistic to apply these kinds of tests to all such suspicious or probable chemicals. Thus some theoretical methods must be developed for this purpose. However the conventional QSAR (quantitative structure activity relationships) approach is of limited relevance to this problem, because these methods do not take detailed mechanisms of molecular interactions in biological systems into account. Thus we have developed a database complex system that enables one to trace molecular interactions triggered by interaction of receptors with xenobiotic chemicals. The main components of this database complex are a potential endocrine disruptor database, a receptor database, a cell signaling networks database, a transcription factor database, and an affinity binding database based on modes of actions.
Database Management Systems↗
The antiestrogen ICI 182,780 inhibits proliferation of human breast cancer cells by interfering with multiple, sequential estrogen-regulated processes required for cell cycle completion.
Antiestrogens are widely used for breast cancer treatment, where they act primarily by inhibiting the mitogenic action of estrogens on tumor cells. The effects of the pure antiestrogen ICI 182,780 on estrogen-regulated cell cycle phase-specific events were investigated here in synchronously cycling human breast cancer (HBC) cells. In early G(1)-arrested MCF-7 or ZR-75.1 cells, 17beta-estradiol (E2) induces rapid activation of the cyclin/Cdk/pRb pathway, as demonstrated by D-type G(1) cyclins accumulation during the first few hours of hormonal stimulation, followed by sequential accumulation of E, A and B1 cyclins and progressive pRb phosphorylation, as cells progress through the cell cycle. When added to quiescent cells together with E2, ICI 182,780 prevents all of the above hormonal effects. Interestingly, in mid-G(1) cells (2-8 h into estrogen stimulation) the antiestrogen causes rapid reversal of hormone-induced D-type cyclins accumulation and pRb phosphorylation, and still fully inhibits G(1)-S transition rate, while in late-G(1) cells it does not prevent S phase entry but still inhibits significantly DNA synthesis rate, S-phase cyclins accumulation and pRb hyperphosphorylation. These results indicate that pure antiestrogens prevent multiple estrogen-induced cell cycle-regulatory events, each timed to allow efficient G(1) completion, G(1)-S transition, DNA synthesis and cell cycle completion.
Breast Neoplasms↗
Effect of tamoxifen on sperm fertilising ability and preimplantation embryo development.
Recent evidences point to a role of estrogens in males. We have earlier reported that tamoxifen, a synthetic non-steroidal antiestrogen, when administered to adult male rats, in the dose range of 0.04-0.4 mg/kg per day, reduced fertility. The reduced fertility was measured in terms of fertility index (a measure of the efficiency of the ovulated ovas to fertilise and implant), fecundity (siring ability) and litter size. The present study was done to investigate whether the reduction in fertility index was due to reduction in fertilising ability or increase in pre-implantation embryo loss. Also a dose related effect of tamoxifen from 0.02 mg to 2 mg/kg per day on the fertility of the male rats was studied. To study the fertilising ability, control and tamoxifen (0.4 mg/kg per day, the most effective dose) treated adult male rats were mated with normal cycling females and the females sacrificed at day 0-4 of gestation. Eggs fertilised/unfertilised were flushed from the oviduct/uterus and the number and types of eggs were noted. The index of fertilisation, a measure of the fertilising ability was determined. The studies demonstrate that the reduction in fertility is not due to decreased fertilising ability but because of the increased pre-implantation embryo loss as evident from an increase in number of abnormal eggs in the treated group with no change in index of fertilisation. A dose related decrease in fertility was observed. The present study suggests that tamoxifen at 0.02-2-mg dose is predominantly estrogenic in males and paternal factor/s sensitive to tamoxifen is involved in embryogenesis.
Animals↗
Estrogenic/antiestrogenic activity of homoisoflavonoids from bulbs of Muscari racemosum (L.) Miller.
The homoisoflavonoid fraction obtained from the Muscari racemosum bulb ether extract (MRBEE) exhibited estrogenic activity by inducing proliferation of MCF7 cells in a dose-dependent manner. In the presence of estradiol MRBEE exhibited a dose-dependent antiestrogenic activity.
Adenocarcinoma↗
Effect of tibolone compared with sequential hormone replacement therapy on carbohydrate metabolism in postmenopausal women.
OBJECTIVE: To investigate the effects of tibolone on carbohydrate metabolism, and to compare these effects with those of a sequential regimen of conjugated equine estrogens and medrogestone. METHODS: This was an open-label, multicentre, comparative study. Seventy-two postmenopausal women were randomized to receive either tibolone 2.5 mg/day or conjugated equine estrogens 0.6 mg plus sequential medrogestone 5 mg (CEE/M) for six 28-day cycles. Carbohydrate metabolism was evaluated at baseline and after three and six cycles of treatment by an oral glucose tolerance test (OGTT). A blood sample was taken at 30, 60, 90 and 120 mm after glucose 75 mg dosing for determination of plasma glucose, insulin and connecting peptide (C-peptide) levels. RESULTS: The changes from baseline of glucose, insulin and C-peptide area-under-the-curve (AUC) values were not statistically significant after 3 and 6 months of tibolone or CEE/M treatment. There was a small transitory decrease in HbA(1C) after three cycles of treatment with tibolone. CONCLUSION: The effects of tibolone and CEE/M on carbohydrate metabolism were considered to have no clinical significance.
Blood Glucose↗
Effect of tibolone on breast symptoms resulting from postmenopausal hormone replacement therapy.
OBJECTIVE: To evaluate the incidence of breast symptoms in a population treated with various hormone replacement therapy (HRT) regimens and to detect the variations in breast symptomatology after HRT changing to tibolone administration. METHODS: This prospective placebo-controlled clinical trial was conducted on healthy women on HRT reporting breast symptoms. A questionnaire was given to each woman to detect breast symptomatology. Breast tenderness and mastalgia were evaluated using a visual analogue scale (VAS). According to the choice of the each woman with breast symptoms, the HRT was changed to tibolone (2.5 mg/day per os) or to calcium carbonate (1 tab/day, placebo group). The duration of treatment was of 12 months. After 6 and 12 months breast symptomatology was re-evaluated. RESULTS: Among the 600 screened women, 64 (10.7%) were suffering from breast symptomatology. After 6 and 12 months of treatment with tibolone or placebo, mean VAS score for breast tenderness and for mastalgia resulted significantly (P<0.05) decreased, without differences between groups, in comparison with basal value. Only one woman had no improvement from the breast symptoms with tibolone administration. CONCLUSIONS: Shifting from classical HRT to tibolone is followed by a significant reduction of breast symptomatology in postmenopausal women with breast complaints similar to that obtained with treatment withdrawal.
Breast↗
The effects of hormone replacement therapy type on pulmonary functions in postmenopausal women.
OBJECTIVE: To study whether hormone replacement therapy (HRT) or Tibolone has an effect on pulmonary function in postmenopausal women. METHODS: Seventy-five postmenopausal women without any risk factor for pulmonary disease were included in this randomized, prospective study. Fifty women had undergone natural menopause and 25 had had a hysterectomy/ooforectomy. Twenty-five natural menopause women were randomly allocated to two groups: 25 patients (Group I) were treated with Tibolone 2.5 mg/day, 25 patients (group II) with Estradiol Hemihidrate 2 mg+Norethindron Asetate 1 mg/day. Twenty-five induced menopause women were treated with 17 beta-estradiol 2 mg/day. Lung function tests including forced vital capacity (FVC), forced expiratory volume (FEV(1)), FEV(1)/FVC, forced expiratory flow rate over the 25-75% of the forced vital capacity volume (FEF(25-75%)), and peak expiratory flow rate (PEF) were evaluated at the beginning and 3 months after the treatment to assess the effects of HRT and Tibolone on respiratory function. RESULTS: Regardless of HRT types a significant difference was observed in FVC and FEV(1) after 3 months of the therapy (P=0.001, 0.0001, respectively). No significant difference was found between pre and post therapy values in the other parameters (P>0.05). CONCLUSIONS: We determined a significant increase in FVC and FEV(1) parameters of pulmonary functions after 3 months of the therapy regardless of HRT types. Therefore, we think that HRT regimens have modifying effects on pulmonary function in postmenopausal women.
Adult↗
Menopause and the central nervous system: intervention options.
The central nervous system is an important target for sex steroid hormones. During the climateric period the rapid decline of gonadal steroids causes neuroendocrine changes in different areas of the brain. The failure of gonadal hormone production brings specific symptoms due to the central nervous system derangement. At the hypotalamic level estrogen withdrawal gives rise to vasomotor symptoms, eating behavior disorders and altered blood pressure control. Psychological disturbances such as depression, anxiety, irritability and mood fluctuation are related to estrogen-induced changes in the lymbic system. The hypothesis of specific neuroanatomical and neurophysiological effects of estrogen on the brain may also explain the correlation between estrogen deficiency and cognitive disturbances such as Alzheimer's type dementia (AD). The increasing interest in the influence of sex steroids on brain function has focused attention on hormonal replacement therapy. Clinical and epidemiological studies have demonstrated that estrogen therapy exerts a positive effect on vasomotor instability and improves psychological disturbances. The positive effects of estrogen on mood are probably related to its stimulatory action on adrenergic and serotoninergic tone. Estrogen may influence the cognitive function through different biological actions. Estrogen administration increases total cerebral and cerebellar blood flow, cerebral glucose administration and improves cholinergic tone, a key neurotransmitter in learning and memory. The evidence suggests that hormone replacement therapy may reduce the relative risk of developing AD. Progestagens and androgen may also have a role in the control of mood disorders. At present, few data are available regarding the influence that selective estrogen receptor modulators, a new class of compounds, can exert on the brain.
Alzheimer Disease↗
Antifertility activity of Derris brevipes variety coriacea.
Traditional physicians in and around Kotagiri village near Ootacamund, use a mixture of powdered roots of Cassia occidentalis, Derris brevipes variety coriacea and Justicia simplex to control female fertility. A mixture of powdered roots of these three plants, powdered root of Derris brevipes variety coriacea and its ethanolic extract were screened for antifertility activity in proven fertile female rats at 200 and 600 mg/kg body weight, respectively and given orally on D(1-7) of pregnancy. Both doses of the root powder of Derris brevipes variety coriacea showed 50% anti-implantation activity and also a significant reduction in the number of litters born. The ethanolic extract exhibited 40% anti-implantation activity when given orally at 600 mg/kg body weight. The rats, which continued their pregnancy, did not deliver any litters after their full term. Hence, the combined antifertility (anti-implantation and abortifacient) activity of the ethanolic extract was 100%. The results suggest that the ethanolic extract possesses more abortifacient type effect than the anti-implantation activity. The ethanolic extract also exhibited weak estrogenic activity when given alone and tested in immature ovariectomised female albino rats. But, when given along with ethinyl estradiol, it exhibited slight antiestrogenic activity. Histological and biochemical estimations were carried out to confirm this.
Abortifacient Agents↗
Post-coital antifertility activity of Acalypha indica L.
Four successive solvent extracts of the whole plant Acalypha indica L. (Euphorbiaceae) were tested for post-coital antifertility activity in female albino rats. Of these, the petroleum ether and ethanol extracts were found to be most effective in causing significant anti-implantation activity. The antifertility activity was reversible on withdrawal of the treatment of the extracts. Both the extracts at 600 mg/kg body weight showed estrogenic activity. Histological studies of the uterus were carried out to confirm this estrogenic activity.
Administration, Oral↗
Reproductive hormones and cardiovascular disease mechanism of action and clinical implications.
The bulk of the experimental data suggest beneficial effects of estrogen (both premenopausal use of OCs and postmenopausal use of ERT-HRT). An intriguing finding from the monkey studies is that social subordination, which induces estrogen deficiency in female monkeys, accelerates atherosclerosis premenopausally and predicts extent of postmenopausal atherosclerosis. This effect can be inhibited by exogenous estrogen, premenopausally. The results suggest that more effort on detecting and regulating premenopausal ovarian dysfunction may be justified. A complication in understanding estrogen action may be the result of varying extents of arterial damage. For example, primary prevention studies in both postmenopausal animals and women have provided strong evidence of atheroprotection with a variety of estrogens. In contrast, the results of secondary prevention studies [10,12] have in general suggested little cardioprotection with either ERT or HRT. Studies in rabbits suggest the antiatherogenic effect of estrogen may not be present when the endothelium is damaged [64]. The state of the endothelium may be critical for some estrogen actions. For those effects of estrogen that require the ER, be it ERalpha or ERbeta, the presence of the receptor may vary with age, disease state, or type of hormone therapy. If continuous combined HRT therapy decreases ER in the artery as it does in the uterus, this may eliminate those estrogen actions requiring the ER, but not others. Older women who have not been exposed to estrogens for many years may be more sensitive to some estrogen effects, and may need lower doses of ERT-HRT. Recent reports suggest that lower doses of estrogens maintain beneficial effects on lipoproteins and coagulation factors [95], while also requiring lower doses of progestogens to protect the uterus [96]. These beneficial findings are very promising in light of the improvements in CHD risk and decreased stroke risk reported with low-dose estrogens [5]. It ill be interesting to see if CRP is increased with lower doses of estrogens and whether these changes are associated with increased early risk of CHD. Perhaps older women with CHD are also more obese, may have diabetes, and may be more susceptible to inflammatory and thrombotic effects of higher doses of estrogens. There are many questions left unanswered. It is hoped that some of the answers may come from the WHI, which is a large prospective trial assessing ERT and HRT. The age range is also relatively large and may be able to determine if older women respond differently than younger women. Some initial data from the WHI have been made available suggesting a small increased risk in the first 2 years and a trend for decreasing risk in the last months of the first 2 years [34]. Just recently, the CEE + MPA arm of the study was stopped early by the data and-safety monitoring board as the overall health risks exceeded benefits with increases in both breast cancer and CVD [97]. The remainder of the study groups including an estrogen-only arm, are expected to continue until 2005.
Cardiovascular Diseases↗
Exemestane, a new steroidal aromatase inhibitor of clinical relevance.
Breast cancer is the leading cause of death among women and the contribution of circulating oestrogens to the growth of some mammary tumours has been recognized. Consequently, suppression of oestrogen action by inhibition of their biosynthesis at the androstenedione-oestrone aromatization step, by means of selective inhibitors of the enzyme aromatase, has become an effective therapeutic option for the treatment of hormone-dependent breast cancer. Exemestane (6-methylenandrosta-1,4-diene-3,17-dione) is a novel steroidal irreversible aromatase inhibitor recently approved and introduced into the global market under the name Aromasin. The design, laboratory and viable syntheses of exemestane, starting from a variety of steroidal precursors, are presented and discussed. Data from biochemical and pharmacological studies as well as the clinical impact of the compound are briefly reviewed. The drug is an orally active and well-tolerated hormonal therapy for postmenopausal patients with advanced breast cancer that has become refractory to standard current hormonal therapies.
Androstadienes↗
Soy isoflavones' osteoprotective role in postmenopausal women: mechanism of action.
Ovarian hormone deficiency is a major risk factor for osteoporosis. Current therapies emphasize the use of antiresorptive agents, such as estrogen, calcitonin, and bisphosphonates. These therapies are associated with certain risks and side effects making compliance a major obstacle. Recent findings suggest that a class of synthetic and naturally occurring compounds, selective estrogen receptor modulators, e.g. raloxifene and soy isoflavones can offer attractive alternatives. Evidence for bone-sparing effects of isoflavones relies mainly on animal findings supported by a limited number of human studies. These observations suggest that isoflavones exert their effects on bone by stimulating bone formation and at the same time suppressing bone resorption. However, the precise osteoprotective mechanism of isoflavones remains uncertain and awaiting further clarification. From a clinical point of view, larger and longer duration studies are warranted to enable us to draw clear conclusions in regards to the role of isoflavones on bone.
Journal Article↗
Aromatase and COX-2 expression in human breast cancers.
We have investigated aromatase and the inducible cyclooxygenase COX-2 expression using immunocytochemistry in tumors of a series of patients with advanced breast cancer treated with aromatase inhibitors. Aromatase was expressed in 58/102 breast cancers. This is similar to the percentage previously reported for aromatase activity. Interestingly, aromatase was expressed in a variety of cell types, including tumor, stromal, adipose, and endothelial cells. Since prostaglandin E2 is known to regulate aromatase gene expression and is the product of COX-2, an enzyme frequently overexpressed in tumors, immunocytochemistry was performed on the tissue sections using a polyclonal antibody to COX-2. Aromatase was strongly correlated (P<0.001) with COX-2 expression. These results suggest that PGE2 produced by COX-2 in the tumor may be important in stimulating estrogen synthesis in the tumor and surrounding tissue. No correlation was observed between aromatase or COX-2 expression and the response of the patients to aromatase inhibitor treatment. However, only 13 patients responded. Nine of these patients were aromatase positive. Although similar to responses in other studies, this low response rate to second line treatment suggests that tumors of most patients were no longer sensitive to the effects of estrogen. Recent clinical studies suggest that greater responses occur when aromatase inhibitors are used as first line treatment. In the intratumoral aromatase mouse model, expression of aromatase in tumors is highly correlated with increased tumor growth. First line treatment with letrozole was effective in all animals treated and was more effective than tamoxifen in suppressing tumor growth. Letrozole was also effective in tumors failing to respond to tamoxifen, consistent with clinical findings. In addition, the duration of response was significantly longer with the aromatase inhibitor than with tamoxifen, suggesting that aromatase inhibitors may offer better control of tumor growth than this antiestrogen.
Adipocytes↗