Effects of SERMs on important indicators of cardiovascular health: lipoproteins, hemostatic factors, and endothelial function

Different patterns in the risk of newly developed fatty liver and lipid changes with tamoxifen versus aromatase inhibitors in postmenopausal women with early breast cancer: A propensity score-matched cohort study

BACKGROUND

Management of metabolic complications of long-term adjuvant endocrine therapy in early breast cancer remained an unmet need. We aimed to compare the effects of tamoxifen (TMX) and aromatase inhibitors (AIs) on the risk of fatty liver in conjunction with longitudinal changes in the serum lipid parameters.

METHODS

Among 1203 subjects who were taking adjuvant TMX or AI (anastrozole or letrozole) without fatty liver at baseline, those taking TMX or AI were 1:1 matched on the propensity score. The primary outcome was newly developed fatty liver detected on annual liver ultrasonography.

RESULTS

Among 328 matched subjects (mean age 53.5 years, body mass index 22.9 kg/m²), 62 cases of fatty liver in the TMX group and 41 cases in the AI group were detected in a total of 987.4 person-years. The incidence rate of fatty liver was higher in the TMX group than in the AI group (128.7 versus 81.1 per 1000 person-years, P = 0.021), particularly within the first 2 years of therapy. TMX was associated with an increased 5-year risk of newly developed fatty liver (adjusted hazard ratio 1.61, P = 0.030) compared with AI independent of obesity and cholesterol level. Subjects who developed fatty liver had higher triglycerides (TGs) and lower high-density lipoprotein cholesterol (HDL-C) level at baseline than those without, which was sustained during follow-up despite the serum cholesterol-lowering effect of TMX.

CONCLUSIONS

TMX independently increased the 5-year risk of newly developed fatty liver compared with AI in postmenopausal women with early breast cancer. Our findings suggest the need for considering the risk of fatty liver as a different adverse event profile between AI and TMX, particularly in patients with obesity, high TGs and low HDL-C.

Effects of adjuvant aromatase inhibitor therapy on lipid profiles

How aromatase inhibitors affect lipids is of great interest. Compared with tamoxifen, adjuvant anastrozole and letrozole are associated with increased incidences of hypercholesterolemia, while similar data are lacking for exemestane in the adjuvant setting. No significant differences in lipid profiles occurred with extended adjuvant exemestane compared with placebo, but total cholesterol and low-density lipoprotein levels increased significantly above baseline in both groups over 6 months. Likewise, no significant differences in hypercholesterolemia rates occurred between extended adjuvant letrozole and placebo. A lipid substudy further confirmed that letrozole did not significantly alter serum lipids for 36 months compared with placebo. Thus, although aromatase inhibitors lack the lipid-lowering properties of tamoxifen, no significant worsening of lipid levels occurs with their use. Patients would benefit from lifestyle changes and routine monitoring of serum lipids. Breast cancer therapy trials often report serum lipid parameters, but assessing the quality and overall significance of the data can be difficult. Methodology of data collection varies among trials and the concomitant use of lipid-modifying medication is often not reported. This review discusses the current understanding of the influence of lipid levels on cardiovascular risk in women and presents key findings on the effects of adjuvant aromatase inhibitor therapy on lipid profiles.

The effects of polymicrobial sepsis with diabetes mellitus on kidney tissues in ovariectomized rats

OBJECTIVES

Sepsis model was used to understand the role of sustained hyperglycemia and ovariectomy, either separately or concomitantly, on the response of the activity of the nuclear factor kappa B (NF-kappaB) and the oxidative response in kidney.

SUBJECTS

Polymicrobial sepsis was induced by cecal ligation and puncture (CLP). Diabetes was induced in female rats using administration of alloxan. The rats were divided into five groups: sham control (group 1), ovariectomy (group 2), ovariectomy + sepsis (group 3), ovariectomy + diabetes (group 4), and ovariectomy + diabetic + sepsis (group 5).

RESULTS

In kidney tissues, the levels of lipid peroxidation (LPO) and glutathione (GSH) and the activity of catalase (CAT) were higher for groups 3, 4, 5 than the control groups. Superoxide dismutase (SOD) activity was lower for groups 3, 4, 5 than the control groups. We determined that CLP produced injury evident in the kidneys of rats when compared to the control group, whereas the severity of the injury was higher in the diabetes + ovariectomy + CLP group when compared to the CLP group. In immunohistochemical staining, we determined that CLP operation increased NF-kappaB activation. In the ovariectomized, septic, and diabetic group, NF-kappaB activation was significantly higher than other groups.

CONCLUSIONS

Hyperglycemia and ovariectomy severely increased NF-kappaB activation and oxidant levels with the stages of our sepsis model. Ovariectomy resulted in general changes in metabolism, which are seen in the kidney with diabetes under sepsis conditions.

Adjuvant aromatase inhibitor therapy: outcomes and safety

Adjuvant therapy with the third-generation aromatase inhibitors (AIs) anastrozole, letrozole, and exemestane has largely replaced the use of tamoxifen (TAM) as standard adjuvant endocrine treatment for postmenopausal women with hormone-sensitive early breast cancer. Treatment strategies investigated in large, randomized, well-controlled clinical studies include the use of an AI as an upfront replacement for TAM, as an alternative to continued treatment with TAM, and in the extended adjuvant setting after at least 5 years of TAM. The efficacy of AIs over TAM has been demonstrated, particularly in terms of improving disease-free survival (DFS), and reductions in early distant metastasis with AIs may ultimately translate into improved overall survival. As AI therapy offers prolonged DFS, safety is an important concern over the long term. The AIs are better tolerated than TAM in terms of troublesome gynecologic adverse events such as vaginal bleeding and discharge, as well as life-threatening complications such as venous thromboembolic events and endometrial cancer. On the other hand, AI therapy has been associated with losses in bone density and a potential effect on lipids and cardiovascular risk. In trials comparing AIs with TAM, only limited conclusions can be made because of the putative cardioprotective, lipid-lowering, and bone-sparing effects of TAM. Studies comparing AIs with placebo, and/or in healthy women, may be more useful in understanding the long-term safety of adjuvant AI therapy. Results of ongoing safety analyses within some of the large AI trials should provide further insight into the long-term tolerability of AI therapy in the adjuvant setting.

Safety of adjuvant endocrine therapy in postmenopausal women with breast cancer

The use of aromatase inhibitors (AIs) as adjuvant endocrine therapy for hormone-sensitive breast cancer is increasing, as these drugs are more effective than tamoxifen alone in improving disease-free survival in breast cancer patients-whether used in lieu of tamoxifen as upfront therapy or after tamoxifen treatment periods of 2 years or longer. AIs differ from tamoxifen in their mechanism of action, effectively suppressing estrogen levels in postmenopausal women to near-undetectable levels. AI-associated adverse events largely mimic menopausal symptoms, including hot flashes, losses in bone mineral density, gynecologic symptoms, and arthralgias. The AIs lack the infrequent but potentially serious adverse events associated with tamoxifen (eg, endometrial cancer, thromboembolic events, and stroke). Large randomized studies of AIs in the adjuvant setting have not demonstrated an adverse effect on lipids and cardiovascular health, but postmenopausal women receiving AIs are at risk for age-related changes in lipid parameters and an increased risk for cardiovascular events. To optimize the overall benefits of adjuvant endocrine therapy with an AI, patients should be monitored for bone loss and cardiovascular risk factors, and symptoms such as joint pain and vaginal dryness should be anticipated and managed proactively.

Update on the use of aromatase inhibitors in early-stage breast cancer

Aromatase inhibitors are currently included in the 'optimal' management of early-stage breast cancer. Uncertainty remains, however, as to the most appropriate treatment strategy, particularly for newly diagnosed women as they seek to trade off the cost, toxicities and efficacy of the treatment options. Recent publications provide conflicting advice on the role of aromatase inhibitors in the treatment of postmenopausal patients with early-stage hormone receptor-positive breast cancer. This review provides updates on the clinical trials of aromatase inhibitors in early breast cancer and tries to provide practical clinical guidance on their optimal use.

Are all aromatase inhibitors alike?

The anti-estrogen tamoxifen was the gold-standard adjuvant therapy for hormone-receptor-positive (HR+) early breast cancer for several decades, but has recently been displaced by the third-generation aromatase inhibitors (AIs). Three AIs are commercially available: letrozole, anastrozole and exemestane. All are more effective and at least as well tolerated as tamoxifen as adjuvant therapy for HR+ breast cancer in postmenopausal women. Despite the wealth of data comparing AIs with tamoxifen, it is unclear whether the three AIs are clinically equivalent, owing to the lack of head-to-head trials directly comparing them. Preclinical and small clinical studies suggest that letrozole is the most potent inhibitor of aromatase, reducing circulating estrogen levels to a greater degree than the other agents. However, whether this greater activity translates into superior clinical efficacy remains to be determined. In the absence of direct comparative data, cross-trial comparisons have been used to gain insights into any safety or efficacy differences. All three AIs have been compared directly with tamoxifen, and efficacy relative to tamoxifen has been compared across trials, although such analyses are complicated by differences in treatment schedules, patient populations and trial designs. Definitive conclusions cannot yet be drawn, but some important differences are coming to light, with upfront letrozole appearing particularly effective at preventing early distant metastasis, an event strongly associated with breast-cancer-related death. No safety differences between the AIs have yet been identified. This article explores the pharmacologic and clinical differences between the AIs, based on data from clinical and preclinical studies.

Understanding the BIG results: Insights from the BIG 1-98 trial analyses

Third-generation aromatase inhibitors (AIs), including letrozole, are now standard therapy for initial adjuvant endocrine treatment of postmenopausal women with early breast cancer. The International Breast Cancer Study Group's Breast International Group (BIG) 1-98 trial is examining efficacy and safety of letrozole or tamoxifen, whether used upfront or sequentially, for postmenopausal with hormone receptor-positive breast cancer. Women in the BIG 1-98 trial were randomized to either 5 years' monotherapy with tamoxifen or letrozole (trial arms A and B, respectively), or to 5 years' sequential therapy with 2 years of tamoxifen followed by 3 years of letrozole, or 2 years of letrozole followed by 3 years of tamoxifen (arms C and D, respectively). Results of the primary core analysis (PCA) of BIG 1-98, at a median follow-up of 25.8 months, showed a significant improvement in disease-free survival for patients treated with initial adjuvant letrozole relative to those on tamoxifen (P=0.003). Of interest, there was an important reduction in distant metastases, the most common and ultimately fatal type of early recurrence, for patients allocated to initial letrozole compared with initial tamoxifen. Since the PCA, there have been further analyses of BIG 1-98 with variations in the cohorts analyzed and follow-up period. The first and largest central pathology review in an adjuvant AI trial to date was also performed in the BIG 1-98 trial. In light of the impending sequence analysis, expected in late 2008, the goal of this article is to describe and summarize the breadth of information learned to date and highlight the key findings regarding the efficacy and safety of letrozole in the initial adjuvant setting.

The effects of caffeic acid phenethyl ester (CAPE) on TNBS-induced colitis in ovariectomized rats

AIM

The aim of this investigation was to examine the effects of caffeic acid phenethyl ester (CAPE) on the development of colitis and antioxidant parameters in bilateral ovariectomized rats subjected to trinitrobenzene sulfonic acid (TNBS)-induced colitis.

MATERIALS AND METHODS

Twenty-one Wistar Albino ovariectomized female rats were divided into four subgroups (n = 5 or 6) (colitis control, vehicle control, CAPE 10 and 30 mg/kg, respectively). Colitis was induced using an enema of TNBS and ethanol, following which CAPE was administrated for 3 days to induce colitis and effect of CAPE was subsequently evaluated.

RESULTS

Based on microscopic damage scores, there was no difference between rats of the TNBS-colitis and the vehicle-treated groups, whereas treatment with CAPE 10 and 30 mg/kg, respectively, caused a significant reduction in colon injury compared to that observed in rats of the TNBS-colitis and vehicle-treated groups. The histologies of both treatment groups were not significantly different. In terms of the biochemical analyses, myeloperoxidase levels in rats from the CAPE 10 and 30 mg/kg groups were significantly different from that of the colitis control rats; however, the levels of malondialdehyde (MDA), catalase and reduced glutathione (GSH) were only significantly different from the levels found colitis control rats in rats administered 10 mg/kg. The levels of MDA, GSH and SOD in rats given CAPE were also significantly different from those of rats in the vehicle control group. These results were consistent with histological findings.

CONCLUSION

CAPE may have a positive effect on the inflammatory bowel disease treatment process and could, therefore, be used as an adjunct therapy in colitis. These effects of CAPE may occur through antiinflammatory and antioxidant mechanisms.

Reducing the risk of early recurrence in hormone-responsive breast cancer

Following primary treatment for early breast cancer, systemic adjuvant therapy is given to reduce the risk of recurrence by targeting any undetectable micrometastatic deposits. Adjuvant systemic treatment may include endocrine therapy, chemotherapy and antibody therapy, depending on the presence or absence of hormone receptors, HER2 status and the estimated risk of relapse. In recent years, an increasing number of tumor characteristics have been identified that influence the risk of relapse and the likelihood of achieving the desired outcome with a given therapy. Hence, choosing the optimum therapy for early breast cancer is becoming an increasingly complicated task. Decision tools have been developed that can be used by physicians to select the most appropriate therapy on an individual basis. Treatment recommendations are, therefore, based on available data from a large number of sources. Hormone-receptor positivity (HR+) is the primary factor when considering whether or not patients should receive adjuvant endocrine therapy. For several decades, tamoxifen has been the gold standard of endocrine therapy, and has significantly reduced recurrences and deaths among the millions of women with HR+ breast cancer worldwide. However, prolonged use of tamoxifen is associated with potentially life-threatening side effects, and resistance is a common problem. In fact, many women will experience disease relapse while on tamoxifen. In particular, the peak of early relapses that occurs in the first 2-3 years after surgery is not prevented by tamoxifen. The third-generation aromatase inhibitors (AIs), letrozole, anastrozole and exemestane, have recently been shown to significantly improve outcomes compared with tamoxifen in large, randomized, controlled trials; however, how the AIs should be incorporated into adjuvant therapy to optimize outcomes requires further investigation. Clinical differences between the AIs, and whether tumor estrogen/progesterone receptor status and HER2 overexpression affect the response to AI therapy, are among the questions that remain to be answered. Ongoing and future studies will help to address these questions and, together with improved patient and disease profiling, will help physicians to optimize adjuvant treatment for individual patients.

The potential antioxidant effect of raloxifene treatment: a study on heart, liver and brain cortex of ovariectomized female rats

The antioxidant activity of some compounds buffer the free radicals generated either endogenously or exogenously, thus decreasing the potential damage mediated by oxidation. Recent studies documented that raloxifene has antioxidant properties in vitro. However, there are limited animal studies available to show raloxifene's antioxidant properties. We aimed to investigate the effects of raloxifene on antioxidant enzymes such as SOD, CAT and GPX, TrxR and the levels of GSH and MDA in heart, liver and brain cortex of ovariectomized female rats. Female Sprague Dawley rats weighing 300-350 g (n=24) were divided into three groups: (I) Eight non-ovariectomized rats were used as naive controls without any treatment (non-ovariectomized group, n=8). Five weeks after ovariectomy, (II) Ovariectomized placebo group (n=8) was given physiological saline, and (III) Raloxifene group (n=8) was given raloxifene 1 mg/kg sc. daily for 12 days. Ovariectomy induced significant increases on SOD, GPX, CAT activity and MDA levels in brain, heart and liver tissues compared to non-ovariectomized rats ( p<0.05). Raloxifene treatment led to decreased levels of SOD activity in heart, GPX activity in brain and CAT activity in liver tissue when compared to ovariectomized group ( p<0.05) but there was no change in activity of TrxR in all groups. The levels of MDA in brain, heart and liver tissues increased in ovariectomized group when compared to non-ovariectomized rats ( p<0.05). Raloxifene had a significant attenuating effect on the levels of MDA in brain and heart tissues. Our results also indicate that the levels of GSH in brain, heart and liver tissue decreased when compared to non-ovariectomized rats. Raloxifene treatment was observed to significantly increase the levels of GSH in brain and heart tissues ( p<0.05). However, there were insignificant differences for the GSH levels in liver tissues of ovariectomized placebo or raloxifene groups. In conclusion, our results demonstrate that raloxifene may be more effective against oxidative stress in heart and brain than in liver tissue.

Safety profiles of tamoxifen and the aromatase inhibitors in adjuvant therapy of hormone-responsive early breast cancer

Adjuvant endocrine therapy plays an important role in the management of hormone-receptor-positive early breast cancer, and has increased life expectancy for millions of women. Many patients receive adjuvant treatment for at least 5 years following tumor resection, hence good long-term safety is important for endocrine agents to gain widespread acceptance. Tamoxifen has been used as adjuvant therapy for early breast cancer for many years, and safety data have been well documented, but a poor risk:benefit profile limits treatment duration to 5 years. Increased efficacy over tamoxifen and good tolerability have recently made the third-generation aromatase inhibitors (AIs) the first-choice agents for adjuvant endocrine therapy; however, it is currently not known whether AI therapy, like tamoxifen, will be limited to 5 years. Many side effects of endocrine therapy, such as hot flushes and mood disturbances, are related to estrogen deprivation and are common to tamoxifen and AIs, reflecting the mechanism of action of these drugs. In addition, tamoxifen has estrogenic effects that are beneficial in some tissues: tamoxifen lowers serum cholesterol levels and protects against bone loss and cardiovascular disease, but is also associated with potentially life-threatening side effects, such as endometrial cancer and thromboembolic disease. As AIs lack estrogenic activity, they are not associated with these serious adverse events. Clinical trials comparing AIs with tamoxifen in the adjuvant setting have shown that AIs are well tolerated and are associated with a lower incidence of gynecological symptoms and hot flushes than tamoxifen. However, AIs are associated with musculoskeletal side effects, such as arthralgia, myalgia and bone loss, but these events are preventable or manageable. The effects of AIs on lipid metabolism and the cardiovascular system are still debatable, but placebo-controlled trials provide no evidence to suggest that AIs adversely affect these systems. Furthermore, the AIs allow women to maintain a good quality of life, comparable with women receiving tamoxifen or placebo, and are a cost-effective therapeutic option. Ongoing trials will provide more information regarding the long-term effects of AI therapy and will provide comparative data on the efficacy and safety of the different AIs, thereby helping to determine the optimal treatment strategy for these highly effective and well-tolerated drugs.

Clinical management of adverse events in adjuvant therapy for hormone-responsive early breast cancer

Systemic adjuvant therapy has proven highly effective at reducing recurrences and deaths in patients who have received primary therapy for early breast cancer. However, as with all treatments, adjuvant therapy can cause unwanted side effects, and effective management of these events is essential to ensure that patients comply with, and continue, treatment. Adjuvant endocrine therapy is not associated with the more severe, acute toxicities of chemotherapy, and can therefore be taken for many years. At present, the standard duration of postoperative adjuvant endocrine therapy is 5 years. Prevention and treatment of adverse events associated with long-term endocrine therapy is particularly important in the adjuvant setting, where patients are clinically cancer free. In this situation, the efficacy benefits are not, therefore, obvious to the patient, but side effects may have a negative impact on daily life. Tamoxifen has been the gold standard endocrine therapy for hormone-receptor-positive early breast cancer for many years, and the long-term side effects of this agent are well documented. In recent years, the aromatase inhibitors (AIs) have begun to displace tamoxifen as the adjuvant therapy of choice, owing to greater efficacy and good tolerability. Predictably, the AIs and tamoxifen have partially overlapping side-effect profiles. Both therapies are associated with typical symptoms of estrogen deprivation; however, tamoxifen also has estrogenic activity in some tissues, which can cause either detrimental (genital tract) or beneficial (bone, cardiovascular system, lipids) effects that are not associated with AI use. To reduce treatment discontinuations, it is important that patients are made aware of the possible side effects of adjuvant therapy and the management strategies available to them, prior to starting therapy. The role of physical, alternative and pharmaceutical therapies in the management of adverse events associated with endocrine therapy has been investigated, and strategies are now available to alleviate symptoms and enable patients to benefit from adjuvant endocrine therapy without a significant adverse impact on quality of life.

Optimal treatment strategies in hormone-responsive early breast cancer: the role of aromatase inhibitors

Results from large controlled clinical trials have identified the third-generation aromatase inhibitors (AIs) as the first significant therapeutic advance in the adjuvant treatment of hormone receptor-positive (HR+) early breast cancer in postmenopausal women since the introduction of tamoxifen. Although all 3 agents, letrozole, exemestane and anastrozole, provide benefits compared with a 5-year course of tamoxifen, the optimum strategy for adjuvant AI therapy has not yet been defined. AIs have been studied upfront, in sequence with tamoxifen, in therapy switch strategies after 2-3 years of tamoxifen, and after the completion of standard adjuvant tamoxifen. Clearly, only upfront treatment with an AI can address the peak risk of relapse during the first 2-3 years after surgery, and both letrozole and anastrozole significantly reduce relapses compared with tamoxifen in this setting. Switching to exemestane or anastrozole benefits women who are disease-free following 2-3 years of tamoxifen, and women who have successfully completed the standard 5 years of tamoxifen can benefit from extended adjuvant letrozole therapy. Ongoing studies will help to determine the optimum treatment strategy, and answer other important questions, such as whether the AIs differ clinically, what influence HR expression profiles have on outcomes, and what long-term toxicities may be associated with these highly effective agents.

Effects of raloxifene and continuous combined hormone therapy on haemostasis variables: A multicenter, randomized, double-blind study

INTRODUCTION

Hormone replacement therapy is known to increase the risk of thromboembolic events. We compared the effects of HRT and raloxifene on some haemostasis variables.

MATERIALS AND METHODS

In a multicenter, double-blind study, 54 healthy postmenopausal women were randomized to receive either continuous treatment with 2 mg 17beta-estradiol plus 1 mg norethisterone acetate (n=30) or 60 mg raloxifene (n=24) daily for 12 months. Blood samples were collected at baseline and at 3, 6 and 12 months to evaluate therapy effects on some haemostasis variables (factor VII, factor VIII, prothrombin fragments 1 and 2, protein C, protein C activity, protein S, thrombin-antithrombin complex, D-dimer, antithrombin, fibrinogen and plasminogen activator inhibitor).

RESULTS

Both raloxifene and continuous combined hormone therapy modified the haemostasis variables toward a more prothrombotic profile. Factor VIII (p<0.01) and fibrinogen (p<0.05) plasma levels significantly increased at 6 months, prothrombin fragments 1 and 2 (p<0.05) significantly increased at 12 months, whereas protein C activity (p<0.001) and antithrombin (p<0.01) significantly decreased at 12 months in both groups.

CONCLUSIONS

Our results demonstrate that raloxifene and continuous combined hormone therapy exhibit the same prothrombotic profile. Both treatments induced an increase in procoagulant parameters at 6 months and a decrease in anticoagulant parameters at 12 months.

Aromatase Inhibitors in the Adjuvant Treatment of Postmenopausal Women with Early Breast Cancer: Putting Safety Issues into Perspective

Tamoxifen has been the gold standard adjuvant therapy for the treatment of postmenopausal women with hormone-receptor-positive (HR+) early breast cancer for many years. Tamoxifen treatment is limited to 5 years because of the development of de novo and acquired resistance, and an ongoing risk of adverse events, including endometrial cancer, thromboembolic events, and gynecological symptoms with long-term use. The third-generation aromatase inhibitors (AIs), letrozole, anastrozole, and exemestane, are displacing tamoxifen as the first-choice therapy for HR+ early breast cancer, and are now recommended as the preferred therapy by national and international guidelines. Recent randomized trials have demonstrated that the AIs are more effective than tamoxifen in preventing disease recurrence when used in substitution and sequential strategies in the early adjuvant setting, and letrozole has been shown to be more effective than placebo in the extended adjuvant setting (after 5 years of tamoxifen therapy). Trial safety data show that the overall tolerability of AIs is similar to that of tamoxifen, with adverse events being predictably characteristic of estrogen deprivation; however, some important differences in adverse event profiles between tamoxifen and the AIs have been demonstrated. In addition to antiestrogenic effects, tamoxifen acts as an estrogen agonist in some tissues, which can lead to serious side effects not associated with the AIs, which prevent estrogen biosynthesis. A lower incidence of gynecological and thromboembolic events is observed in patients taking AIs, and fewer cases of endometrial cancer are seen compared with tamoxifen. Adverse events that are more frequent with adjuvant AI therapy compared with tamoxifen include arthralgia and myalgia, bone loss, and effects on the cardiovascular system and blood lipids. The effects of AIs on bone are predictable and may be easily managed, where necessary, with bisphosphonates. Studies examining the effects of AIs on the cardiovascular system and lipid profiles, including in the extended adjuvant setting, suggest that these adverse events may be due to the absence of a protective effect of tamoxifen rather than true AI toxicity. Further studies are required to determine the long-term safety of AI therapy in postmenopausal women with HR+ early breast cancer.

Initial versus sequential adjuvant aromatase inhibitor therapy: a review of the current data

OBJECTIVE

One of the principle unresolved questions in adjuvant endocrine therapy for breast cancer is whether it is more beneficial for women to receive aromatase inhibitor (AI) monotherapy or start with tamoxifen and then switch to AI therapy. This review will compare the current available efficacy, safety, and cost-effectiveness data for AIs in the initial adjuvant and switch adjuvant settings.

METHODS

A search of the Medline database from 1976 through 2006 was performed for the following terms: breast cancer, adjuvant, aromatase inhibitors, anastrozole, letrozole, exemestane, tamoxifen, sequential, switching. A search for relevant abstracts from the EBCC, ECCO, ASCO, and SABCS conferences was also performed.

RESULTS

In the upfront adjuvant setting, anastrozole and letrozole have both demonstrated a significant disease-free survival (DFS) benefit over tamoxifen. Upfront therapy with a nonsteroidal AI appears to be most critical for patients at risk of an early relapse, illustrated by the finding that upfront letrozole provided a significant early DFS advantage over tamoxifen only in patients with node-positive disease (hazard ratio = 0.71, p < 0.001). With respect to safety, both strategies have similar adverse event profiles. From an economic perspective, AIs, whether used upfront or sequentially, are considered cost-effective compared with tamoxifen due to the cost savings associated with a reduction in the breast cancer event rate. From the efficacy standpoint, modeling studies have produced inconsistent results and do not produce definitive data.

CONCLUSIONS

Differences in patient populations, definitions of end points, and prior tamoxifen usage between the trials discussed necessitates a careful interpretation but may provide insights in the treatment decision-making process. The BIG 1-98 trial was designed to compare letrozole monotherapy versus a letrozole-to-tamoxifen or reverse-sequence approach and should provide insights to the question of optimal therapy. Until results are available, for higher-risk patients (i.e., those with positive lymph nodes), initiation of treatment with a non-steroidal AI may be beneficial to avoid tamoxifen-associated early relapses that occur in the first 2 years after diagnosis.

Safety of adjuvant aromatase inhibitor therapy

The long-term effects of aromatase inhibitors (AIs) on lipids and bone and cardiovascular and gynecological health are of particular interest to clinicians. The safety data of anastrozole, letrozole, and exemestane are limited to trials with follow-up periods of 5 years or less, and much of the data arise from comparisons with tamoxifen, a drug that has both estrogen agonist and antagonist effects. With the lack of extensive long-term data, indirect comparisons between the safety profiles of the AIs provide some insights. Although results from these indirect comparisons should be interpreted cautiously, they may assist physicians in the decision-making process. Thus far, AIs confer an increased risk of bone loss and osteoporosis and fractures, while the effects on lipid profiles and cardiovascular health seem to indicate only that AIs lack the cardioprotective and lipid-lowering effects of tamoxifen. Some data also are available from comparisons with placebo, a more appropriate comparator to investigate the tolerability and safety of a specific drug. In the MA.17 trial, patients receiving letrozole experienced similar rates of cardiovascular ischemic events and hypercholesterolemia compared with those on placebo. The significant clinical benefits of AIs compared with tamoxifen have been achieved without worsening quality of life.

Appraising Adjuvant Aromatase Inhibitor Therapy

Tamoxifen, once the gold standard adjuvant endocrine therapy for early breast cancer, is being challenged by third-generation aromatase inhibitors (AIs) that have demonstrated improved disease-free survival in a variety of adjuvant settings for early breast cancer. Tamoxifen and AIs have different safety profiles, which should allow physicians to begin to individualize treatment based on a patient's comorbidities and risk factors. Because of its properties as a partial estrogen agonist, tamoxifen has a positive effect on serum lipids and may confer a cardioprotective benefit, as well as a beneficial effect on bone health. However, tamoxifen increases the risk for endometrial cancer and cerebrovascular/thromboembolic events. In comparison, the major side effect of AIs is increased bone loss, which may heighten the risk for osteoporotic fractures and bone pain. Because of their superior efficacy and manageable side effects, AIs are a cost-effective alternative to tamoxifen, and clinical guidelines now embrace AIs as appropriate adjuvant therapy for hormone-sensitive early breast cancer. The anticipated results of ongoing trials will provide further insights into the long-term safety and application of AI therapy in the adjuvant setting.

Incidence and management of side effects associated with aromatase inhibitors in the adjuvant treatment of breast cancer in postmenopausal women

OBJECTIVE

Third-generation aromatase inhibitors (AIs) are effective and generally well-tolerated as adjuvant therapy. These AIs are now being introduced for the adjuvant treatment of postmenopausal patients with estrogen-receptor-positive early-stage breast cancer. However, questions remain about their long-term safety. This paper summarizes the adverse events reported in third-generation AI trials and comments on the appropriate management of these drug-induced adverse events in patients.

METHODS

Papers relating to anastrozole, exemestane, and letrozole were identified through Medline searches, and proceedings of recent oncology meetings were also reviewed to capture relevant emerging data.

RESULTS

The most commonly reported adverse events associated with adjuvant AI therapy include hot flushes and musculoskeletal complaints/arthralgia. The incidence of endometrial cancer and thromboembolic events is significantly lower with an AI than with tamoxifen. However, there is a small but significant increase in the risk of osteoporosis and fractures with AI therapy. A potential negative effect on the cardiovascular system, specifically on lipid metabolism, has not been conclusively demonstrated. No significant differences in overall quality of life were observed in studies comparing AIs with tamoxifen or placebo.

CONCLUSION

AIs alone and sequenced after tamoxifen are an appropriate option for adjuvant endocrine therapy for most postmenopausal patients with hormone-responsive breast cancer. The incidence of some side effects such as endometrial cancer, stroke, or pulmonary embolism associated with tamoxifen is decreased. Monitoring and management of bone loss associated with AI treatment are essential and are being addressed in ongoing trials. Further studies with longer follow-up are required to clarify the effects of AIs on lipid metabolism and cardiovascular health.

Coronary heart disease and stroke with aromatase inhibitor, tamoxifen, and menopausal hormone therapy use

Results from the Women's Health Initiative randomized clinical trials of hormone therapy provide the clinical context for interpreting tamoxifen and aromatase inhibitor (AI) findings regarding coronary heart disease (CHD) and stroke. Of note is the potential link between increased stroke risk and increased dementia risk seen with the use of estrogen alone and the combination of estrogen/progestin. Like hormone therapy, tamoxifen has been found to generally lower low-density lipoprotein and total cholesterol but increase triglyceride levels. The preponderance of clinical evidence suggests that tamoxifen increases stroke risk and has no effect or modestly reduces CHD risk. Aromatase inhibitors generally do not influence low-density lipoprotein cholesterol and could modestly increase high-density lipoprotein cholesterol and reduce triglyceride levels. Current but limited evidence suggests that AIs have a modest increase or no effect on CHD as a class or as individual agents compared with tamoxifen. The influence of AIs on stroke is unsettled, and within-class differences might exist. In the adjuvant breast cancer setting, based on available evidence, the influence of AIs on CHD or stroke will infrequently influence overall patient outcome. If remaining issues are to be addressed, more rigorous CHD and stroke assessment procedures are needed in future trials evaluating AIs.

Letrozole as adjuvant endocrine therapy in postmenopausal women with breast cancer

The third-generation aromatase inhibitor letrozole offers a promising approach to treating hormone-sensitive breast cancer for postmenopausal women, through potent and specific inhibition of estrogen synthesis. In neoadjuvant and first-line treatment, letrozole demonstrated superior efficacy compared with tamoxifen in randomized Phase III trials. Initial results of Breast InterGroup 1-98, a large ongoing randomized trial investigating primary adjuvant endocrine treatment with either letrozole or tamoxifen, have recently been presented. Patients treated with letrozole demonstrated a 19% improvement in disease-free survival and a significant reduced risk of distant recurrences, holding out the prospect of a survival advantage over tamoxifen treatment with further maturation of the trial. For patients who have already completed 5 years of tamoxifen, extended endocrine therapy with letrozole is a new therapeutic option based on the results of the MA-17 trial. The optimal use of aromatase inhibitors remains an open question, at least until results from randomized trials (BIG 1-98, TEAM) investigating the sequential use of an aromatase inhibitor and tamoxifen in comparison with continuous monotherapy become available.

Cardiovascular Health and Aromatase Inhibitors

Cardiovascular disease is the most frequent cause of death in North American women, and so death resulting from cardiovascular disease, rather than from malignancy, is not uncommon in breast cancer patients. This may be a consequence of the shared risk factors for developing breast cancer and cardiovascular disease, as well as the difficulty of managing cancer patients at higher risk for developing cardiovascular disease. Recently, much attention has focused on understanding the cardiovascular risk factors associated with breast cancer therapies. Tamoxifen has a lowering effect on serum lipids and is reported to decrease the risk of myocardial infarction but to increase the risk of thromboembolic events. Current data indicate that aromatase inhibitors (AIs) are not associated with an increased risk of thromboembolic or cerebrovascular events. Reports of a greater incidence of hypercholesterolaemia when AIs are compared head-to-head with tamoxifen may be a result of the intrinsic lipid-lowering effects of tamoxifen therapy and may be confounded by differences in data collection among trials. The incidence of cardiovascular events associated with AIs in large trials has been reported to be higher in trials comparing AIs with tamoxifen; comparisons within the MA.17 trial, which evaluated an AI versus placebo, did not show increases in hypercholesterolaemia or in cardiovascular events with the AI. When treating breast cancer patients, oncologists should consider the same positive lifestyle changes that are proposed to lower the risk of cardiovascular disease in patients who do not have breast cancer. Moreover, physicians should assess cardiovascular risk, and monitor and treat patients already diagnosed with or at risk for coronary heart disease, according to established guidelines.

A comparison of letrozole and tamoxifen in postmenopausal women with early breast cancer

BACKGROUND

The aromatase inhibitor letrozole is a more effective treatment for metastatic breast cancer and more effective in the neoadjuvant setting than tamoxifen. We compared letrozole with tamoxifen as adjuvant treatment for steroid-hormone-receptor-positive breast cancer in postmenopausal women.

METHODS

The Breast International Group (BIG) 1-98 study is a randomized, phase 3, double-blind trial that compared five years of treatment with various adjuvant endocrine therapy regimens in postmenopausal women with hormone-receptor-positive breast cancer: letrozole, letrozole followed by tamoxifen, tamoxifen, and tamoxifen followed by letrozole. This analysis compares the two groups assigned to receive letrozole initially with the two groups assigned to receive tamoxifen initially; events and follow-up in the sequential-treatment groups were included up to the time that treatments were switched.

RESULTS

A total of 8010 women with data that could be assessed were enrolled, 4003 in the letrozole group and 4007 in the tamoxifen group. After a median follow-up of 25.8 months, 351 events had occurred in the letrozole group and 428 events in the tamoxifen group, with five-year disease-free survival estimates of 84.0 percent and 81.4 percent, respectively. As compared with tamoxifen, letrozole significantly reduced the risk of an event ending a period of disease-free survival (hazard ratio, 0.81; 95 percent confidence interval, 0.70 to 0.93; P=0.003), especially the risk of distant recurrence (hazard ratio, 0.73; 95 percent confidence interval, 0.60 to 0.88; P=0.001). Thromboembolism, endometrial cancer, and vaginal bleeding were more common in the tamoxifen group. Women given letrozole had a higher incidence of skeletal and cardiac events and of hypercholesterolemia.

CONCLUSIONS

In postmenopausal women with endocrine-responsive breast cancer, adjuvant treatment with letrozole, as compared with tamoxifen, reduced the risk of recurrent disease, especially at distant sites. (ClinicalTrials.gov number, NCT00004205.)

Procoagulant state after raloxifene therapy in postmenopausal women

OBJECTIVE

To investigate the effects of raloxifene on the hemostatic system in postmenopausal women.

DESIGN

A prospective longitudinal study.

SETTING

Outpatient clinic of the Faculty of Medicine of Ribeirão Preto, Brazil.

PATIENT(S)

Sixteen postmenopausal women aged 56.8 +/- 5.9 years (mean +/- SD).

INTERVENTION(S)

Raloxifene hydrochloride (60 mg once daily) was administered orally for a period of 6 months.

MAIN OUTCOME MEASURE(S)

Plasma activities of coagulation factors (II, V, VII, VIII, IX, X, XI, XII, and fibrinogen), prothrombin-derived fragment 1+2, and activated protein C (APC) sensitivity ratio were measured at baseline and after 1, 3, and 6 months of treatment.

RESULT(S)

Factor VIII activity increased by 17.1% and 26.9% at 3 and 6 months of treatment, respectively, compared with baseline. Factor XI and FXII activities significantly increased by 10.9% and 43.1%, respectively, after 6 months compared with baseline. A significant reduction of APC sensitivity ratio also was observed after 6 months of treatment.

CONCLUSION(S)

A procoagulant state characterized by increased factor VIII, XI, and XII plasma levels and by reduced APC sensitivity was observed after raloxifene therapy in post-menopausal women.

The Effect of Tamoxifen and Fluoride on Bone Mineral Density, Biomechanical Properties and Blood Lipids in Ovariectomized Rats

The most important aspect of therapy with fluoride and tamoxifen concerns its influence on bone tissue and lipid metabolism. The aim of the study was to evaluate the effect of tamoxifen and natrium fluoride (NaF) on bone metabolism, biochemical properties and blood lipids levels in ovariectomized rats. The study was performed in Wistar rats divided into 5 subgroups: ovariectomized controls, rats treated with NaF 20 mg/kg/24 hr, rats treated with NaF 20 mg/kg/24 hr+tamoxifen 2 mg/kg/24 hr, rats treated with NaF 20 mg/kg/24 hr plus tamoxifen 4 mg/kg/24 hr, and sham-operated controls. In ovariectomized rats the increase of total cholesterol, low-density lipoproteins cholesterol (LDL-cholesterol) as well as the decrease of bone mineral content, bone mineral density and biomechanical properties was observed. The therapy with NaF increased the level of total cholesterol, LDL-cholesterol, triglycerides, bone mineral density, bone mineral content. In this group the decrease of bone strength and stiffness was observed. The administration of tamoxifen reduced the changes in plasma lipid levels, but did not improve the biomechanical properties of bone tissue.

Tamoxifen improves endothelial function and reduces carotid intima-media thickness in postmenopausal women

BACKGROUND

Tamoxifen is a selective estrogen-receptor modulator shown to improve several cardiovascular risk factors in postmenopausal women with breast cancer. In animal studies tamoxifen inhibits the progression of atherosclerosis. Although the presence of a history with tamoxifen treatment is related to a lower intima-media thickness (IMT) of the common carotid artery, data from controlled follow-up studies are lacking to support this observation.

METHODS

We examined 14 postmenopausal women with early stage breast cancer with indication for tamoxifen treatment (20 mg/d) and 13 healthy postmenopausal women. Flow-mediated dilatation (FMD) of the brachial artery, combined carotid IMT, and aortic pulse wave were measured before and 6 months after treatment in the tamoxifen group and at the same times in the control group.

RESULTS

FMD and IMT were significantly increased and decreased, respectively, in the treatment group compared to the control group (FMD: +2.2% +/- 0.9% vs +0.085% +/- 1%, P =.012; IMT: -0.088 +/- 0.03 mm vs +0.04 +/- 0.03 mm, P =.018, mean +/- standard error of the mean, treatment vs control group). These differences remained significant even when adjusted for age, duration of menopause, and cardiovascular risk factors. Low-density lipoprotein cholesterol was also significantly reduced after tamoxifen treatment.

CONCLUSIONS

Tamoxifen treatment slows the progression of atherosclerosis in postmenopausal women with breast cancer as assessed by changes in carotid IMT. An improvement in endothelial function and blood lipid profile may be the reason for this beneficial effect.