Randomized trial of bilateral oophorectomy versus tamoxifen in premenopausal women with metastatic breast cancer

Endoxifen, an Estrogen Receptor Targeted Therapy: From Bench to Bedside

The selective estrogen receptor (ER) modulator, tamoxifen, is the only endocrine agent with approvals for both the prevention and treatment of premenopausal and postmenopausal estrogen-receptor positive breast cancer as well as for the treatment of male breast cancer. Endoxifen, a secondary metabolite resulting from CYP2D6-dependent biotransformation of the primary tamoxifen metabolite, N-desmethyltamoxifen (NDT), is a more potent antiestrogen than either NDT or the parent drug, tamoxifen. However, endoxifen's antitumor effects may be related to additional molecular mechanisms of action, apart from its effects on ER. In phase 1/2 clinical studies, the efficacy of Z-endoxifen, the active isomer of endoxifen, was evaluated in patients with endocrine-refractory metastatic breast cancer as well as in patients with gynecologic, desmoid, and hormone-receptor positive solid tumors, and demonstrated substantial oral bioavailability and promising antitumor activity. Apart from its potent anticancer effects, Z-endoxifen appears to result in similar or even greater bone agonistic effects while resulting in little or no endometrial proliferative effects compared with tamoxifen. In this review, we summarize the preclinical and clinical studies evaluating endoxifen in the context of breast and other solid tumors, the potential benefits of endoxifen in bone, as well as its emerging role as an antimanic agent in bipolar disorder. In total, the summarized body of literature provides compelling arguments for the ongoing development of Z-endoxifen as a novel drug for multiple indications.

Management of ER positive metastatic breast cancer

There are over 2 million cases a year of breast cancer, leading to over 600,000 deaths globally [1]. Despite these large numbers, increasingly more women are being cured with early stage disease and women with advanced disease are living longer [2]. The appreciation for molecular subtypes of the disease has led to significant therapeutic advances and estrogen receptor positive (ER+) breast cancer represents the largest of these subgroups. An appreciation for the importance of estrogen signaling in ER+ dates back to 1896 when Dr. George Thomas Beatson observed impressive disease responses after performing bilateral oophorectomy in 3 women at Glasgow Cancer Hospital [3]. The evolution of treatment for advanced disease from progestins, to the selective estrogen receptor modulator tamoxifen, and subsequently the aromatase inhibitors and the selective estrogen receptor degrader fulvestrant, has been accompanied by improved efficacy and decreased side effects. While the use of these drugs has changed the natural history of both early and advanced disease, it has been long recognized that many patients will develop resistance to this approach. After many years of trying to improve on single-agent endocrine treatment, since 2012 there has been an explosion of new drugs that have shown improved efficacy in combination with endocrine approaches. The first of these to receive FDA approval was the mTOR inhibitor everolimus (2012) [4], followed by the approval of 3 cyclin-dependent kinase 4 and 6 (CDK 4/6) inhibitors [palbociclib (2015) [5], ribociclib (2018) [6], and abemaciclib (2018) [7]], and more recently the PI3-kinase inhibitor alpelisib (2019) [8]. In addition, chemotherapy is still used frequently when endocrine manipulations have been exhausted. Like other incurable malignancies, the goal in advanced ER+ breast cancer is to prolong survival and maintain quality of life. Currently, we have more tools available to achieve this than ever before and we will review the efficacy and side effect data with these agents that are driving physician choices for individual patients.

Review of concepts in therapeutic decision-making in HER2-negative luminal metastatic breast cancer

Purpose

Hormone receptor (HR)-positive, Human epidermal growth factor receptor 2 (HER2)-negative metastatic breast cancer (MBC) requires a therapeutic approach that takes into account multiple factors, with treatment being based on anti-estrogen hormone therapy (HT). As consensus documents are valuable tools that assist in the decision-making process for establishing clinical strategies and optimize the delivery of health services, this consensus document has been created with the aim of developing recommendations on cretiera for hormone sensitivity and resistance in HER2-negative luminal MBC and facilitating clinical decision-making.

Methods

This consensus document was generated using a modification of the RAND/UCLA methodology, which included the definition of the project and identification of issues of interest, a non-exhaustive systematic review of the literature, an analysis and synthesis of the scientific evidence, preparation of recommendations, and external evaluation with a panel of 64 medical oncologists specializing in breast cancer.

Results

A Spanish panel of experts reached consensus on 32 of the 32 recommendations/conclusions presented in the first round and were accepted with an approval rate of 100% about definition of metastatic disease not susceptible to local curative treatment, definition of hormone sensitivity and hormone resistance in metastatic luminal disease and therapeutic decision-making.

Conclusion

We have developed a consensus document with recommendations on the treatment of patients with HER2-negative luminal MBC that will help to improve therapeutic benefits.

Fulvestrant plus goserelin versus anastrozole plus goserelin versus goserelin alone for hormone receptor-positive, HER2-negative tamoxifen-pretreated premenopausal women with recurrent or metastatic breast cancer (KCSG BR10-04): a multicentre, open-label, three-arm, randomised phase II trial (FLAG study)

BACKGROUND

We investigated the efficacy and safety of fulvestrant plus goserelin (F + G) versus anastrozole plus goserelin (A + G) in comparison with goserelin (G) alone in premenopausal women with hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-), tamoxifen-pretreated metastatic breast cancer (MBC).

PATIENTS AND METHODS

In this multicentre, open-label, randomised phase II study, premenopausal women aged ≥18 years with HR+, HER2-, tamoxifen-pretreated MBC were randomly assigned (1:1:1) to F + G, A + G or G alone. The primary end-point was time to progression (TTP). Secondary end-points included overall survival, overall response rate, clinical benefit rate and toxicity.

RESULTS

Of 138 eligible patients, 44 were randomly assigned to receive F + G, 47 to A + G and 47 to G alone. The median follow-up duration was 32.2 months (interquartile range: 23.69-40.86) and the median age was 43.0 years (range 23.0-55.0). The median TTP was 16.3 months (95% confidence interval [CI] 7.5-25.1) for F + G, 14.5 months (95% CI 11.0-18.0) for A + G and 13.5 months (95% CI 10.3-16.8) for G alone. Compared with G alone, the hazard ratios were 0.608 for F + G (95% CI, 0.370-0.998; p = 0.049) and 0.982 for A + G (95% CI, 0.624-1.546; p = 0.937). In terms of visceral metastasis, a stratification factor, there were no TTP differences according to treatment arm. Grade III or IV toxicities were rarely observed. Of the common adverse events, grade I arthralgia and joint stiffness were more frequently observed in the F + G than in the A + G or G-alone groups (p < 0.05, respectively).

CONCLUSIONS

F + G provides a promising new option for the treatment of premenopausal women with HR+, HER2-, tamoxifen-pretreated MBC.

TRIAL REGISTRATION

ClinicalTrials.gov number NCT01266213 and Korean Cancer Study Group (KCSG) Breast cancer protocol number BR10-04.

Endocrine Therapy in Premenopausal Hormone Receptor Positive/Human Epidermal Growth Receptor 2 Negative Metastatic Breast Cancer: Between Guidelines and Literature

There is growing interest in the endocrine treatment (ET) of premenopausal women with hormone receptor positive (HR+) metastatic breast cancer (MBC). This review summarizes available data on endocrine therapy for this patient subset and aims to define the most appropriate treatment approach. The combination of luteinizing hormone-releasing hormone (LHRH) agonists plus tamoxifen seems effective and safe and is considered as being superior to either approach alone; still, single-agent therapy remains an acceptable treatment option. Due to their mechanism of action, aromatase inhibitors alone are not suitable for the treatment of premenopausal patients, but the combination with LHRH agonists may result in excellent disease control. Fulvestrant, in conjunction with LHRH agonists, also yields interesting results regarding clinical benefit rate and time to progression; currently, other orally available selective estrogen receptor downregulators are under clinical evaluation. Recently, targeted drugs have been added to ET in order to reverse endocrine resistance, but only limited information regarding their activity in premenopausal patients is available. The cyclin dependent kinase 4 and 6 inhibitor palbociclib when combined with fulvestrant and LHRH agonists was shown to prolong progression-free survival over endocrine therapy alone in pretreated patients; similar results were obtained with the addition of abemacicilib or ribociclib to endocrine therapy. Currently, activity of the mammalian target of rapamycin inhibitor everolimus in combination with letrozole and goserelin is under assessment in premenopausal patients after progression on tamoxifen (MIRACLE trial).

IMPLICATIONS FOR PRACTICE

This review provides clinicians with an overview on the available data regarding endocrine treatment of hormone receptor positive (HR+) metastatic breast cancer (MBC) in premenopausal women and summarizes the treatment options available in routine clinical practice. Knowledge of an up-to-date therapeutic approach in women with premenopausal HR+ MBC will lead to better disease management, thereby improving disease control and quality of life while minimizing side effects.

Embryonic transcription factor SOX9 drives breast cancer endocrine resistance

The estrogen receptor (ER) drives the growth of most luminal breast cancers and is the primary target of endocrine therapy. Although ER blockade with drugs such as tamoxifen is very effective, a major clinical limitation is the development of endocrine resistance especially in the setting of metastatic disease. Preclinical and clinical observations suggest that even following the development of endocrine resistance, ER signaling continues to exert a pivotal role in tumor progression in the majority of cases. Through the analysis of the ER cistrome in tamoxifen-resistant breast cancer cells, we have uncovered a role for an RUNX2-ER complex that stimulates the transcription of a set of genes, including most notably the stem cell factor SOX9, that promote proliferation and a metastatic phenotype. We show that up-regulation of SOX9 is sufficient to cause relative endocrine resistance. The gain of SOX9 as an ER-regulated gene associated with tamoxifen resistance was validated in a unique set of clinical samples supporting the need for the development of improved ER antagonists.

Effects of ovarian ablation or suppression in premenopausal breast cancer: A meta-analysis of randomized controlled trials

BACKGROUND

The effect of ovarian ablation or suppression (OAS) in premenopausal women with breast cancer is controversial. The overall survival (OS), disease-free survival (DFS) and adverse event of OAS versus no OAS were compared.

METHODS

A literature review of EMBASE, Web of Science, PUBMED, and Cochrane Library was conducted. The hazard ratio (HR) and 95% confidence interval (CI) for OS and DFS, as well as risk ratio (RR) and 95% CI for adverse events were evaluated. I-squared statistic (I²) represents heterogeneity.

RESULTS

Twenty-nine studies with a total of 21,249 women were included. In premenopausal women aged 40 years or younger, there were significant differences in OS (HR 0.78, 95% CI: 0.66-0.94, P=0.008, I² = 0%) and DFS (HR 0.84, 95% CI: 0.73-0.97, P=0.02, I² = 0%) between OAS and no OAS. In advanced stage breast cancer, a significant difference was found in OS (HR 0.76, 95% CI: 0.60-0.96, P=0.02, I² = 0%). Patients treated with OAS had more chances to have hot flushes (RR 1.91, 95% CI: 1.62-2.26, P < 0.01, I² = 0%) and vaginal dryness (RR 1.19, 95% CI: 1.08-1.31, P=0.0003, I² = 0%). No significant difference in depression (RR 1.28, 95% CI: 0.94-1.74, P=0.12, I² = 0%).

CONCLUSIONS

The study shows that OAS plays a beneficial role in premenopausal women aged 40 years or younger and advanced stage breast cancer. However, OAS is associated with increase in hot flushes and vaginal dryness.

Clinical Implications of the Progression-Free Survival Endpoint for Treatment of Hormone Receptor-Positive Advanced Breast Cancer

: Hormonal therapy for advanced breast cancer (ABC) has evolved significantly since the introduction of tamoxifen more than 40 years ago. The availability of selective antiestrogen therapies has further improved treatment options for women with hormone receptor-positive (HR+) ABC. However, with the development of resistance to hormonal therapies, a new treatment paradigm has emerged based on our understanding of biological pathways involved in HR+ breast cancer and mechanisms of resistance to hormonal therapy. Recent drug development efforts have focused on combining hormonal treatment with agents that target mammalian target of rapamycin serine-threonine kinases and cyclin-dependent kinases. In parallel with the evolution of hormonal and targeted therapies, our understanding of the utility of clinical endpoints has deepened. Progression-free survival (PFS) is a primary endpoint well-understood by clinicians and is increasingly accepted as a surrogate for overall survival (OS) by the U.S. Food and Drug Administration. Yet the perceived clinical benefit of PFS to patients is less well understood. Patients may not grasp the implications of prolonged PFS, highlighting the reality that patient preference in treatment selection encompasses factors that extend beyond drug activity. This presents an opportunity for clinicians to discuss PFS with patients in the context of their treatment plans, clinical outcomes, and quality-of-life measures. The objective of this review is to explore the clinical validity of the PFS and OS endpoints and the clinical relevance of PFS and OS to patients, especially in light of drivers that led to a range of treatment options for patients with HR+ ABC.

IMPLICATIONS FOR PRACTICE

Advances in drug development during the past two decades have provided numerous options for treatment of advanced breast cancer that include monotherapy with endocrine modulating agents and dual therapy that combines endocrine therapy with an inhibitor targeting the mammalian target of rapamycin serine-threonine kinase or cyclin-dependent kinase pathways known to be involved with resistance. Clinical trial endpoints for breast cancer have evolved as well. Communication of progression-free survival, overall survival, and other outcomes with patients should incorporate the context of the individual's treatment plan and include discussion of response rate, side effects, and quality of life.

Endocrine Therapy for Hormone Receptor-Positive Metastatic Breast Cancer: American Society of Clinical Oncology Guideline

PURPOSE

To develop recommendations about endocrine therapy for women with hormone receptor (HR) -positive metastatic breast cancer (MBC).

METHODS

The American Society of Clinical Oncology convened an Expert Panel to conduct a systematic review of evidence from 2008 through 2015 to create recommendations informed by that evidence. Outcomes of interest included sequencing of hormonal agents, hormonal agents compared with chemotherapy, targeted biologic therapy, and treatment of premenopausal women. This guideline puts forth recommendations for endocrine therapy as treatment for women with HR-positive MBC.

RECOMMENDATIONS

Sequential hormone therapy is the preferential treatment for most women with HR-positive MBC. Except in cases of immediately life-threatening disease, hormone therapy, alone or in combination, should be used as initial treatment. Patients whose tumors express any level of hormone receptors should be offered hormone therapy. Treatment recommendations should be based on type of adjuvant treatment, disease-free interval, and organ function. Tumor markers should not be the sole criteria for determining tumor progression; use of additional biomarkers remains experimental. Assessment of menopausal status is critical; ovarian suppression or ablation should be included in premenopausal women. For postmenopausal women, aromatase inhibitors (AIs) are the preferred first-line endocrine therapy, with or without the cyclin-dependent kinase inhibitor palbociclib. As second-line therapy, fulvestrant should be administered at 500 mg with a loading schedule and may be administered with palbociclib. The mammalian target of rapamycin inhibitor everolimus may be administered with exemestane to postmenopausal women with MBC whose disease progresses while receiving nonsteroidal AIs. Among patients with HR-positive, human epidermal growth factor receptor 2-positive MBC, human epidermal growth factor receptor 2-targeted therapy plus an AI can be effective for those who are not chemotherapy candidates.

Luteal versus follicular phase surgical oophorectomy plus tamoxifen in premenopausal women with metastatic hormone receptor-positive breast cancer

PURPOSE

In premenopausal women with metastatic hormone receptor-positive breast cancer, hormonal therapy is the first-line therapy. Gonadotropin-releasing hormone analogue + tamoxifen therapies have been found to be more effective. The pattern of recurrence risk over time after primary surgery suggests that peri-operative factors impact recurrence. Secondary analyses of an adjuvant trial suggested that the luteal phase timing of surgical oophorectomy in the menstrual cycle simultaneous with primary breast surgery favourably influenced long-term outcomes.

METHODS

Two hundred forty-nine premenopausal women with incurable or metastatic hormone receptor-positive breast cancer entered a trial in which they were randomised to historical mid-luteal or mid-follicular phase surgical oophorectomy followed by oral tamoxifen treatment. Kaplan-Meier methods, the log-rank test, and multivariable Cox regression models were used to assess overall and progression-free survival (PFS) in the two randomised groups and by hormone-confirmed menstrual cycle phase.

RESULTS

Overall survival (OS) and PFS were not demonstrated to be different in the two randomised groups. In a secondary analysis, OS appeared worse in luteal phase surgery patients with progesterone levels <2 ng/ml (anovulatory patients; adjusted hazard ratio 1.46, 95% confidence interval [CI]: 0.89-2.41, p = 0.14) compared with those in luteal phase with progesterone level of 2 ng/ml or higher. Median OS was 2 years (95% CI: 1.7-2.3) and OS at 4 years was 26%.

CONCLUSIONS

The history-based timing of surgical oophorectomy in the menstrual cycle did not influence outcomes in this trial of metastatic patients. ClinicalTrials.gov number NCT00293540.

Current Medical Treatment of Patients with Non-Colorectal Liver Metastases: Primary Tumor Breast Cancer

BACKGROUND

(Metastatic) breast cancer is a heterogeneous entity in which every disease subtype requires an individualized systemic treatment approach.

METHODS

We reviewed the currently available data regarding systemic therapy of breast cancer and present a review of historical and current treatment approaches, with the publications cited covering a time span from 1896 to the last ASCO 2015.

RESULTS

Systemic therapy of metastatic breast cancer may include chemotherapy, endocrine therapy, and targeted therapies (e.g. antibody-based approaches). Based on the patient's breast cancer subtype, these agents may be employed alone or in combination. Therefore, characterization of the phenotype of the disease is necessary and may include biopsy of the metastatic site. Novel therapeutic approaches include immunologic therapies as well as PARP, PI3K and CDK 4/6 inhibitors, which are currently under investigation in clinical trials.

CONCLUSION

Systemic therapy of metastatic breast cancer requires complex and individualized treatment approaches that are best offered in an interdisciplinary setting.

Endocrine therapy for advanced/metastatic breast cancer

First-line endocrine therapy by estrogen antagonism or suppression of estrogen achieves objective responses (ORs) and clinical benefit (CB) in around 30% and 50% of estrogen receptor-positive metastatic breast cancer patients, respectively. Aromatase inhibitors (AIs) are the most effective treatment in previously untreated postmenopausal women. Tamoxifen is an effective alternative. The optimal endocrine therapy on relapse remains uncertain. Tamoxifen and fulvestrant achieve CB in around 50% of patients and ORs of 10%. CB of exemestane after nonsteroidal AIs is 30% to 50% but ORs are rare. Targeted agents (eg, everolimus) plus endocrine therapy are likely to become increasingly important in overcoming endocrine resistance.

Differential inhibitory potencies and mechanisms of the type I ribosome inactivating protein marmorin on estrogen receptor (ER)-positive and ER-negative breast cancer cells

Breast cancer is the second most common cancer with a high incidence rate worldwide. One of the promising therapeutic approaches on breast cancer is to use the drugs that target the estrogen receptor (ER). In the present investigation, marmorin, a type I ribosome inactivating protein from the mushroom Hypsizigus marmoreus, inhibited the survival of breast cancer in vitro and in vivo. It evinced more potent cytotoxicity toward estrogen receptor (ER)-positive MCF7 breast cancer cells than ER-negative MDA-MB-231 cells. Further study disclosed that marmorin undermined the expression level of estrogen receptor α (ERα) and significantly inhibited the proliferation of MCF7 cells induced by 17β-estradiol. Knockdown of ERα in MCF7 cells significantly attenuated the inhibitory effect of marmorin on proliferation, suggesting that the ERα-mediated pathway was implicated in the suppressive action of marmorin on ER-positive breast cancer cells. Moreover, marmorin induced time-dependent apoptosis in both MCF7 and MDA-MB-231 cells. It brought about G2/M-phase arrest, mitochondrial membrane potential depolarization and caspase-9 activation in MCF7 cells, and to a lesser extent in MDA-MB-231 cells. Marmorin triggered the death receptor apoptotic pathway (e.g. caspase-8 activation) and endoplasmic reticulum stress (ERS, as evidenced by phosphorylation of PERK and IRE1α, cleavage of caspase-12, and up-regulation of CHOP expression) in both MCF7 and MDA-MB-231 cells. In summary, marmorin exhibited inhibitory effect on breast cancer partially via diminution of ERα and apoptotic pathways mediated by mitochondrial, death receptor and ERS. The results advocate that marmorin is a potential candidate for breast cancer therapy.

Current approaches to the management of Her2-negative metastatic breast cancer

While metastatic breast cancer (MBC) remains incurable, a vast array of active therapeutic agents has provided the opportunity for long-term disease control while maintaining quality of life and physical function. Optimal management of MBC balances a multitude of factors, including a woman's performance status, social support, symptoms, disease burden, prior therapies, and surrogates for tumor biology. Choosing the most appropriate initial therapy and subsequent sequence of treatments demands flexibility as goals and patient preferences may change. Knowledge of the estrogen receptor (ER), progesterone receptor (PR), and Her2 receptor status of the metastatic tumor has become critical to determining the optimal treatment strategy in the metastatic setting as targeted therapeutic approaches are developed. Patients with ER⁺ or PR⁺ breast cancer or both have a wide array of hormonal therapy options that can forestall the use of cytotoxic therapies, although rapidly progressive phenotypes and the emergence of resistance may ultimately lead to the need for chemotherapy in this setting. So-called 'triple-negative' breast cancer - lacking ER, PR, and Her2 overexpression - remains a major challenge. These tumors have an aggressive phenotype, and clear targets for therapy have not yet been established. Chemotherapy remains the mainstay of treatment in this group, but biologically based clinical trials of new agents are critical to developing a more effective set of therapies for this patient population.

Algorithms for the treatment of patients with metastatic breast cancer and prior exposure to taxanes and anthracyclines

At present, metastatic breast cancer (MBC) remains an incurable disease, with the goals of care aimed at maximizing the patient's duration and quality of life. Treatment options for a patient with MBC have become more efficacious and numerous. In addition to endocrine and chemotherapy agents, a number of targeted agents, including trastuzumab and bevacizumab, are available. The option to use novel agents combined with a multitude of standard chemotherapies has further enhanced the landscape of therapeutic options. As such, specific regimens must be evaluated within the framework of the individual patient, answering such questions as whether to treat with sequential single agents or combination regimens as well as which agents to use and in what sequence. The concept of personalized care is even more apparent in the setting of MBC, where the goal of palliation is intrinsically more nuanced than that of curative intent. This review will broadly assess the evidence for current treatment options with attention to varying clinical scenarios. Ultimately, delivering quality of care necessitates balancing an understanding of evidence-based data with sensitive attention to quality-of-life goals.

Therapeutic options for metastatic breast cancer

Metastatic breast cancer (MBC) remains an incurable disease despite ongoing therapeutic advances. Recently there has been progress extending the range of available cytotoxic chemotherapy drugs and optimizing their scheduling. In addition, a greater understanding of tumor biology has led to the development of a number of targeted therapies. Several of these newer agents, such as trastuzumab, lapatinib and bevacizumab, have demonstrated activity in combination with chemotherapy and have improved the prognosis of patients with MBC. We hope that further progress elucidating the pathophysiology and biology of MBC will continue to lead to corresponding advances in treatment.

Endocrine therapy of metastatic breast cancer

Breast cancer growth and dissemination is regulated by estrogen and different growth factor receptor signalling pathways. The increasing knowledge of the biology of breast cancer regarding the interaction of these signalling pathways provides a tool to understand endocrine therapies response and resistance mechanisms. In patients with slowly progressive disease, no visceral involvement, and minimal symptoms, endocrine therapy could be the strategy of choice, even if the tumor has low estrogen receptor expression. Ovarian suppression and tamoxifen are recommended for premenopausal patients whether aromatase inhibitors are the option for postmenopausal ones. Chemotherapy still remains as the right alternative for hormone unresponsive or resistant patients. This is a review focused on the different strategies and combinations of endocrine therapies for metastatic breast cancer patients considering the potential strategies clinically tested to overcome resistance and the different treatments of choice available for each scenario of disseminated disease.

North Central Cancer Treatment Group--achievements and perspectives

The North Central Cancer Treatment Group (NCCTG) was founded in 1977 as a regional cooperative group to allow cancer patients in the upper Midwest of the United States to gain access to clinical trials in oncology by establishing a network of community oncology practices with one academic research base, the Mayo Clinic. Since then, the NCCTG has grown into an international cooperative group with 43 members in 33 US states and Canada. This article details 30 years of achievements of the NCCTG, including important scientific contributions from disease-specific and treatment modality committees, the cancer control program, patient-reported outcomes and quality-of-life research, and biostatisticians that support the NCCTG's specific aims: to improve the duration and quality of life of cancer patients, to enhance our understanding of the biological consequences of cancer and its treatment, and to improve methods for clinical trial conduct.

Advances in the treatment of breast cancer

Breast cancer is the most commonly diagnosed cancer in American women and is the second leading cause of cancer-related deaths in this population. This review highlights how the use of a multidisciplinary approach to the management of diseases of the breast and the introduction of novel systemic therapies have improved the quality of life and survival in patients with breast cancer.

Achievements in systemic therapies in the pregenomic era in metastatic breast cancer

Over the last decades, the introduction of several new agents into clinical practice has significantly improved disease control and obtained some, albeit rare, survival benefits in metastatic breast cancer (MBC). Despite these results, the choice of treatment for the majority of patients is still empirically based, since the only two predictive factors with level 1 evidence for clinical use are hormonal receptor status for endocrine therapy and HER-2 status for trastuzumab therapy. Important improvements in the endocrine therapy of both pre- and postmenopausal women with hormone-responsive disease have been achieved. For premenopausal women, ovarian function suppression with luteinizing hormone-releasing hormone analogs combined with tamoxifen has become the standard treatment, although aromatase inhibitors plus ovarian function suppression are under evaluation. In postmenopausal patients, aromatase inhibitors have proved to be superior to standard endocrine therapies in either first- or second-line treatment and a novel antiestrogen compound, fulvestrant, has been introduced in clinical practice. Chemotherapy remains the treatment of choice for hormone unresponsive or resistant patients. Anthracyclines and taxanes have been used either alone or in combination as first-line chemotherapy, but with the more frequent use of these agents in the adjuvant setting, new standards are needed for first-line chemotherapy, and new and more efficacious treatments are required. In the subgroup of patients with tumors that overexpress HER-2, the use of trastuzumab alone or in combination with chemotherapy has modified the natural history of these tumors, even if only about one out of two patients obtains a clinical response. In this review we summarize the main achievements and the currently available treatment options for patients with MBC.

Hormonal therapy for advanced breast cancer

Hormonal therapy for advanced breast cancer has evolved significantly in the more than 100 years since the first publications documenting the effect of ovarian ablation on advanced breast cancer in premenopausal women. Since that time, not only have we developed the methods to measure estrogen and progesterone receptors in cancer cells, but more recently we have understood that expression of these receptors determines response to hormone therapy. The availability of more selective antiestrogen therapies has changed and significantly improved the treatment options for women who have advanced hormone-responsive breast cancer. Current research is focusing on reversing resistance to hormone therapy with the addition of targeted biologic agents to standard hormonal treatment.

Bone loss and the aromatase inhibitors

The increasing use of systemic adjuvant therapies has considerably improved the prognosis from early breast cancer. However, some of these therapies affect bone metabolism, resulting in osteoporosis. Aromatase inhibitors lower circulating oestrogen levels to almost unrecordable levels in postmenopausal women, predisposing them to bone loss with an increase in fracture risk. Ongoing clinical trials are favouring the use of the aromatase inhibitors over tamoxifen and this may advocate greater use of these drugs in the future. Strategies for the identification and management of treatment-induced bone loss are currently being defined.

Beta-interferon and interleukin-2 prolong more than three times the survival of 26 consecutive endocrine dependent breast cancer patients with distant metastases: an exploratory trial

Distant metastases from breast cancer are incurable. In endocrine-responsive patients antiestrogens are commonly administered as first and second line therapy. Regrettably, tumor growth becomes resistant to this relatively innocuous therapy. Beta-interferon was unsuccessfully added to tamoxifen to induce estrogen receptor enhancement. In mice, interleukin-2 added to tamoxifen increased their mutual anti-tumor activities. Nevertheless, no effective clinical application has been developed. We started an exploratory clinical trial based on the association of these immunostimulating cytokines with antiestrogens for first line salvage therapy of hormone dependent breast cancer with distant metastases. Twenty-six consecutive breast cancer patients with distant metastases, 23 of which had metastases at multiple sites, were studied for responsiveness to treatment with first line salvage antiestrogen therapy, combined with beta-interferon and interleukin-2 immuno-therapy. Clinical response and survival were compared with that of 30 consecutive historical control patients treated with antiestrogen therapy alone. Controls showed, as expected, a median duration of response, a median survival time after treatment, and after diagnosis of distant metastases, of 16, 31 and 34 months, respectively. After a mean follow-up of 62+/-36 months (range 17-155), the interval times in the non-control patients were 61 (P<0.001), 101 (P<0.000001) and 106 (P<0.000001) months. Two long-term survivors appeared to be cured after 155 and 94 months from the time of diagnosis with multiple bone metastases. Nineteen of the patients treated with beta-interferon and interleukin-2 have survived. Hormone immuno-therapy was given in an outpatient setting and was very well tolerated. These data suggest that immuno-therapy plays an important role in endocrine-dependent metastatic breast cancer.

Facts and Controversies in Systemic Treatment of Metastatic Breast Cancer

The management of metastatic breast cancer remains an important and controversial issue. The systemic therapy, comprising endocrine, cytotoxic and biological agents, can be administered sequentially or in combination. Few drugs or combinations provide a significant improvement in survival and, therefore, in the great majority of cases, treatment is given with a palliative intent. With the exception of first-line therapy, for which general agreement exists, currently there is no consensual standard of care. This review will summarize the current knowledge and outline the controversial issues related to systemic therapy of metastatic breast cancer, with emphasis on treatment tailoring. The potential role of tumor molecular profile(s) in the selection of patients that could benefit the most from each strategy/agent will be discussed.

What Is the Role of Ovarian Ablation in the Management of Primary and Metastatic Breast Cancer Today?

Ovarian ablation has been used for more than a century in the treatment of breast cancer. Methods of irreversible ovarian ablation include surgical oophorectomy and ovarian irradiation. Potentially reversible castration can be accomplished medically using luteinizing hormone releasing hormone (LHRH) analogues. In addition, cytotoxic chemotherapy unpredictably produces amenorrhea and primary ovarian failure in 10%-95% of premenopausal women as a function of patient age, cumulative dose, and the specific agents used. In the metastatic setting, ovarian ablation and tamoxifen monotherapies produce comparable outcomes and may be more effective when used together. While many early adjuvant trials of ovarian ablation were methodologically flawed, a more recent meta-analysis by the Early Breast Cancer Trialists' Collaborative Group of 12 properly designed randomized trials found significantly greater disease-free and overall survival rates for women under the age of 50, regardless of nodal status, receiving ovarian ablation as a single adjuvant therapy. Several important issues regarding the role of ovarian ablation in the treatment of breast cancer remain unresolved. Data suggest that ovarian ablation followed by some years of tamoxifen produces similar results to those seen with adjuvant chemotherapy in women with hormone-receptor positive breast cancer; however, the value of combining these modalities is still unclear. Other areas of ongoing investigation include the appropriate duration of therapy with LHRH analogues in the adjuvant setting, the long-term sequelae of ovarian suppression among young breast cancer survivors, and refinement of the population most likely to benefit from ovarian ablation or suppression.

Advances in estrogen receptor biology: prospects for improvements in targeted breast cancer therapy

Estrogen receptor (ER) has a crucial role in normal breast development and is expressed in the most common breast cancer subtypes. Importantly, its expression is very highly predictive for response to endocrine therapy. Current endocrine therapies for ER-positive breast cancers target ER function at multiple levels. These include targeting the level of estrogen, blocking estrogen action at the ER, and decreasing ER levels. However, the ultimate effectiveness of therapy is limited by either intrinsic or acquired resistance. Identifying the factors and pathways responsible for sensitivity and resistance remains a challenge in improving the treatment of breast cancer. With a better understanding of coordinated action of ER, its coregulatory factors, and the influence of other intracellular signaling cascades, improvements in breast cancer therapy are emerging.

The use of gonadotrophin-releasing hormone (GnRH) agonists in early and advanced breast cancer in pre- and perimenopausal women

Gonadotrophin-releasing hormone (GnRH) agonists, in particular goserelin ('Zoladex'), are increasingly being used for the treatment of breast cancer in women with functioning ovaries. They act by downregulating pituitary GnRH receptors, thereby suppressing the release of luteinising hormone (LH) and follicle stimulating hormone (FSH), which, in turn, reduce the main source of oestradiol production in the ovaries. GnRH agonists have been shown to be as effective therapeutically as surgical ovarian ablation in pre- and perimenopausal women with advanced breast cancer. The combination of a GnRH agonist such as goserelin with the peripheral oestrogen antagonist, tamoxifen, may be used to produce 'combined oestrogen blockade'. In advanced breast cancer, this regimen prolongs progression-free survival and increases both the response rate and duration relative to the use of a GnRH agonist alone. In patients with early breast cancer, the addition of goserelin to 'standard treatment' (i.e. surgery+/-tamoxifen, chemotherapy or radiotherapy) results in a significant benefit in recurrence-free survival and overall survival. This benefit was most apparent in patients with oestrogen receptor (ER) +ve tumours. Goserelin, when used either alone or in combination with tamoxifen as an adjuvant systemic therapy in women with ER +ve tumours, has been shown in clinical trials to produce recurrence-free survival rates equivalent to cytotoxic chemotherapy such as cyclophosphamide, methotrexate, 5-fluorouracil (CMF). Evidence suggests that at least part of the effect of adjuvant cytotoxic chemotherapy in premenopausal women is produced by ovarian ablation. Endocrine therapy with goserelin or goserelin plus tamoxifen should now be considered a treatment option in the management of premenopausal women with ER +ve early breast cancer.

Pharmacological profile of MEN 11066, a novel potent and selective aromatase inhibitor

MEN 11066 is a new non-steroidal compound which potently inhibits human placenta (K(i)=0.5 nM) and rat ovarian (K(i)=0.2 nM) aromatase in vitro. In vivo, a single oral dose of 0.3 mgkg(-1) significantly decreased uterus weight in immature rats after stimulation of uterus growth by androstenedione. MEN 11066 reduced in a dose-dependent manner plasma estradiol levels in adult female rats treated with pregnant mare serum gonadotropin (PMSG). After 2 weeks of repeated daily treatment in adult rats, a significant decrease in uterine weight was observed together with a 65% decrease in plasma estradiol, whereas plasma levels of testosterone, progesterone, aldosterone, corticosterone, cholesterol, LH and FSH were not affected. The lack of any effect by MEN 11066 on adrenal steroids was confirmed by the unchanged plasma corticosterone and aldosterone levels in immature rats and also in adult rats when the repeated treatment with MEN 11066 (15 days) was followed by the administration of a synthetic ACTH analogue. No change in 11beta-hydroxylase or 21-hydroxylase activities was produced in vitro by the addition of 10 microM MEN 11066. Fifteen-day treatment with MEN 11066 did not produce changes in several rat hepatic enzymatic activities involved in the metabolism of xenobiotics. These results demonstrated that MEN 11066 is a potent inhibitor of aromatase which does not interfere with the cytochrome P450 involved in the synthesis of other steroids or in the metabolism of xenobiotics.

Will the experience with tamoxifen in breast cancer help define the role of antiandrogens in prostate cancer?

Breast and prostate cancers are the two predominant hormone-responsive tumours. The use of the antioestrogen tamoxifen in the treatment of breast cancer has evolved over the past 30 y from treatment for advanced breast cancer to prevention. Tamoxifen is currently the endocrine treatment of choice for advanced breast cancer and for adjuvant therapy in a broad spectrum of women whose primary tumours have functional oestrogen receptors. It has also been shown to reduce the incidence of breast cancer in high-risk women. Non-steroidal antiandrogen therapy is used in the treatment of prostate cancer, but its role is still being defined. The clinical development of tamoxifen and that of the antiandrogens are reviewed and parallels are uncovered which provide insight into contemporary and future management of hormone-responsive prostate cancer.Prostate Cancer and Prostatic Diseases (2001) 4, 72-80

Management of premenopausal women with early-stage breast cancer: is there a role for ovarian suppression?

There is an overwhelming body of evidence that adjuvant ovarian ablation/suppression has a favorable impact on survival for premenopausal women with hormone-responsive early-stage breast cancer. This article reviews the randomized controlled trials that provide these data and the indirect evidence suggesting that much of the benefit seen for adjuvant chemotherapy in estrogen receptor-positive patients < 50 years of age is an indirect consequence of a chemical castration. Therefore, carefully selected women may have a choice of ovarian suppression with a gonadotropin-releasing hormone (GnRH) analogue, such as goserelin, as an alternative to chemotherapy, which would allow younger premenopausal women to retain fertility. In addition, if chemotherapy is selected and the patient does not develop permanent amenorrhoea, then additional treatment with a GnRH analogue is indicated.

Use of SERMs for the adjuvant therapy of early-stage breast cancer

Tamoxifen was the first in a class of drugs now commonly referred to as selective estrogen receptor modulators or SERMs. SERMs exhibit tissue-specific estrogenic agonist/antagonist activity through their ability to bind to the estrogen receptor alpha (ER) protein and interact with coregulatory proteins, thereby modulating transcription of estrogen target genes. Since its first approval by the United States Food and Drug Administration (FDA) in 1977, tamoxifen has been found to (a) lower the risk of recurrence and death for women with early-stage hormone receptor-positive breast cancer, irrespective of menopausal and node status or use of adjuvant chemotherapy; (b) reduce the risk of invasive breast cancer following breast conservation in women with ductal carcinoma in situ (DCIS); and (c) reduce the risk of breast cancer in high-risk women. Toremifene is the only other SERM approved by the FDA for breast cancer treatment. However, it offers no clear clinical advantage over tamoxifen in the adjuvant or metastatic settings. Several other SERMs are in various phases of clinical development. In addition, strategies to combine SERMs with other endocrine therapy like ovarian suppression or aromatase inhibitors are active areas of investigations. At present, SERMs are recognized as the first targeted and relatively nontoxic medical therapy for women with high-risk or steroid hormone receptor-positive breast cancer.

Combined tamoxifen and luteinizing hormone-releasing hormone (LHRH) agonist versus LHRH agonist alone in premenopausal advanced breast cancer: a meta-analysis of four randomized trials

PURPOSE

The logic behind the application of luteinizing hormone-releasing hormone (LHRH) agonists in combination with tamoxifen in premenopausal women is that LHRH agonists on the one hand suppress the tamoxifen-induced stimulation of the pituitary-ovarian function and, on the other hand, seem as effective as surgical castration. This meta-analysis combines all randomized evidence to compare the combined treatment with LHRH agonist alone with respect to overall survival, progression-free survival, and objective response in premenopausal women with advanced breast cancer.

PATIENTS AND METHODS

Four clinical trials randomizing a total of 506 premenopausal women with advanced breast cancer to LHRH agonist alone or to the combined treatment of LHRH agonist plus tamoxifen were identified. Meta-analytic techniques were used to analyze individual patient data from these trials.

RESULTS

With a median follow-up of 6.8 years, there was a significant survival benefit (stratified log-rank test, P = .02; hazards ratio [HR] = 0.78) and progression-free survival benefit (stratified log-rank test, P = .0003; HR = 0.70) in favor of the combined treatment. The overall response rate was significantly higher on combined endocrine treatment (stratified Mantel Haenszel test, P = .03; odds ratio = 0.67).

CONCLUSION

The combination of LHRH agonist plus tamoxifen is superior to LHRH agonist alone in premenopausal women with advanced breast cancer. Therefore, if a premenopausal woman with advanced breast cancer is thought to be suitable for endocrine treatment, it is proposed that the combination of a LHRH agonist plus tamoxifen be considered as the new standard treatment.

Gynecologic effects of tamoxifen: case reports and review of the literature

The literature regarding the gynecologic effects of tamoxifen contains very little data on the vagina and lower urinary tract. The authors present two patients receiving tamoxifen who had gynecologic surgery complications that could be associated with tamoxifen use. Both patients had poor healing which improved when the tamoxifen was discontinued. Possible explanations are given for this observation based on what is known about this unusual drug. Owing to the success of tamoxifen in breast cancer patients, its use is currently being extended to include groups of healthy women at risk for the development of breast cancer. Because the number of women receiving tamoxifen may be increasing the authors include a review of its effects, with which all health care providers caring for women should be familiar.

Current and future directions in medical therapy for breast carcinoma: endocrine treatment

Endocrine therapy remains a mainstay of treatment for breast carcinoma in both adjuvant and metastatic settings. The choice of endocrine therapy is guided by the presence and degree of expression of estrogen receptor (ER) and progesterone receptor (PgR) as well as by clinical parameters. Adjuvant tamoxifen (TAM) given for 5 years is accepted standard therapy for postmenopausal ER and/or PgR positive (+ve) women. In premenopausal women, 5 years of TAM given alone has similar effects, but is used less frequently because chemotherapy has been regarded as a standard even in ER and PgR +ve women. Recent literature has demonstrated the equivalence or superiority of (Zoladex [ZOL], Zeneca Pharmaceuticals, Wilmington, DE) goserelin acetate plus TAM to cyclophosphamide, methotrexate, and 5-fluorouracil (CMF) chemotherapy in premenopausal ER and PgR +ve women. This, together with older data showing equivalence or superiority of ovarian ablation (OA) to CMF chemotherapy in the same setting, as well as accumulating data suggesting benefit from the addition of ZOL, OA, and/or TAM to chemotherapy in the premenopausal adjuvant setting, has raised issues regarding whether ZOL, OA, and/or TAM can substitute for chemotherapy or should always be added to it for premenopausal receptor +ve women. In the metastatic setting, the second-generation aromatase inhibitors (AI) clearly have moved into position as second-line therapy after TAM. Recent data have shown equivalence and perhaps some superiority to TAM by at least one AI (anastrazole [AN]) in first-line metastatic treatment. The results of adjuvant studies comparing TAM, AN, and TAM + AN in the adjuvant setting will be awaited with great interest. In the interim, the development of other SERMS (raloxifene, EM 850) and of pure antiestrogens may provide new and exciting approaches in the metastatic, adjuvant, and preventive settings.

Systematic reviews of chemotherapy and endocrine therapy in metastatic breast cancer

Metastatic breast cancer is incurable but often responsive to treatment. There is little evidence-based consenus on when to use which treatments, in what combination and for how long. Systematic reviews were performed on 12 prospectively defined, clinically relevant research questions to support the development of evidence-based clinical practice guidelines. A comprehensive search of Medline from 1966 to 1996 identified over 1800 controlled trials. Eligibility and data extraction were performed independently by two blinded reviewers. Trial results were summarised by ratios of median survivals (RMS) and P -values for survival curve comparisons with meta-analysis by weighted combination of these statistics. Sixty-five publications reporting 97 treatment comparisons were included. There was moderate evidence that more rather than fewer cycles of chemotherapy improved survival (RMS:1.23, P -0.01). The evidence did not support: higher rather than lower doses of chemotherapy (or of endocrine therapy); any one class of endocrine agent over all others; multiple endocrine agents over a single agent; or, combined chemotherapy and endocrine therapy over either single modality. Only six trials assessed quality of life revealing better quality of life with more rather than fewer cycles of chemotherapy and with standard rather than lower doses of chemotherapy. These systematic reviews reveal counterintuitive evidence useful to everyday practice, in particular that more rather than fewer cycles of chemotherapy lead to better quality of life and longer survival.

Altering the estrogenic milieu of breast cancer with a focus on the new aromatase inhibitors

Aromatase is a dual-enzyme complex that catalyzes the synthesis of estrogen from androgenic precursors. Although evidence implicates estrogens in the pathogenesis of breast cancer, recent findings suggest that deregulation of aromatase may be a crucial link between these hormones and this neoplasm. Whereas tamoxifen is the endocrine therapy of choice, selective inhibition of aromatase may be equally effective, and possibly less toxic, in the management of patients with hormone-responsive breast tumors.

New generation aromatase inhibitors in breast cancer. Weighing out potential costs and benefits

Endocrine therapy is the oldest and still one of the most effective forms of systemic therapy for breast cancer. Unfortunately, only one-third of all breast carcinomas respond to a strategy that modifies the activity of estrogen at the level of the tumour. Therefore, it is important that patients with cancer likely to respond are reliably identified. Substantial evidence indicates that tumour estrogen receptor level is the best predictor of response to hormonal therapy. Although antiestrogen therapy is still considered the endocrine modality of choice for all stages of breast cancer, there is renewed interest in finding new agents with improved therapeutic indices. The development of agents which selectively suppress aromatase, a key enzyme in estrogen biosynthesis, can be attributed not only to the importance of extraglandular aromatase activity, but also to the unparalleled success of tamoxifen. The present status, emerging roles and concerns of the new aromatase inhibitors are discussed in order to assess their potential costs and therapeutic merit.

The role of LH-RH analogues in the adjuvant and palliative treatment of breast cancer

Ovarian ablation has a long-standing history in the treatment of metastatic breast cancer. At the end of the past century, several reports appeared on the beneficial effect of surgical removal of the ovaries in premenopausal women with advanced breast cancer. Subsequently, this treatment became the standard systemic hormone therapy for such patients. However, the disadvantage is that only a minority of patients respond, and the remainder suffer unnecessary treatment morbidity. In a random premenopausal patient population, oophorectomy produced an average 33% objective response rate. In the search for alternatives, analogues of luteinizing hormone-releasing hormone (LH-RH) have been thoroughly investigated in pre- and postmenopausal women. The results obtained have established a place for LH-RH agonists in the treatment of premenopausal women with metastatic breast cancer. In addition, these substances have replaced oophorectomy where indicated in the adjuvant hormonal treatment of premenopausal breast cancer.