Scottish adjuvant tamoxifen trial: a randomized study updated to 15 years

Recommandations francophones pour la pratique clinique concernant la prise en charge des cancers du sein de Saint-Paul-de-Vence 2022-2023

With more than 60,000 new cases of breast cancer in mainland France in 2023 and 8% of all cancer deaths, breast cancer is the leading cancer in women in terms of incidence and mortality. While the number of new cases has almost doubled in 30 years, the percentage of patients at all stages alive at 5 years (87%) and 10 years (76%) testifies to the major progress made in terms of screening, characterisation and treatment. However, this progress, rapid as it is, needs to be evaluated and integrated into an overall strategy, taking into account the characteristics of the disease (stage and biology), as well as those of the patients being treated. These are the objectives of the St Paul-de-Vence recommendations for clinical practice. We report here the summary of the votes, discussions and conclusions of the Saint-Paul-de-Vence 2022-2023 RPCs.

The beneficial effects of tamoxifen on arteries: a key player for cardiovascular health of breast cancer patient

Breast cancer is the most common cancer in women. Over the past few decades, advances in cancer detection and treatment have significantly improved survival rate of breast cancer patients. However, due to the cardiovascular toxicity of cancer treatments (chemotherapy, anti-HER2 antibodies and radiotherapy), cardiovascular diseases (CVD) have become an increasingly important cause of long-term morbidity and mortality in breast cancer survivors. Endocrine therapies are prescribed to reduce the risk of recurrence and specific death in estrogen receptor-positive (ER+) early breast cancer patients, but their impact on CVD is a matter of debate. Whereas aromatase inhibitors and luteinizing hormone-releasing hormone (LHRH) analogs inhibit estrogen synthesis, tamoxifen acts as a selective estrogen receptor modulator (SERM), opposing estrogen action in the breast but mimicking their actions in other tissues, including arteries. This review aims to summarize the main clinical and experimental studies reporting the effects of tamoxifen on CVD. In addition, we will discuss how recent findings on the mechanisms of action of these therapies may contribute to a better understanding and anticipation of CVD risk in breast cancer patients.

Extended adjuvant endocrine therapy for women with hormone receptor-positive early breast cancer: A meta-analysis with trial sequential analysis of randomized controlled trials

OBJECTIVES

The aim of the current study is to explore the association between extended adjuvant endocrine treatment and prognosis of women with hormone receptor-positive (HR+) early breast cancer.

METHODS

Databases including PubMed, Web of Science, Embase and the Cochrane Library databases were electronically searched to identify randomized controlled trials (RCTs) that reported extended endocrine therapy for women with HR+ early breast cancer. The retrieval time was limited from inception to September 2022. Two reviewers independently screened literature, extracted data, and assessed risk bias of included studies. Meta-analysis was performed by using R software Version 4.1.2 and STATA Version 12.0.

RESULTS

A total of 15 RCTs involving 29497 cases were included. The overall analysis showed that compared with the control, extended adjuvant endocrine therapy increased disease-free survival (DFS) (HR=0.814, 95% CI: 0.720-0.922, 95% PI: 0.556-1.194), overall survival (OS) (HR=0.885, 95% CI: 0.822-0.953, 95% PI: 0.771-1.035), relapse-free survival (RFS) (HR=0.833, 95% CI: 0.747-0.927, 95% PI: 0.575-1.159), distant metastatic-free survival (DMFS) (HR=0.824, 95% CI: 0.694-0.979, 95% PI: 0.300-2.089) and reduced new breast cancer cumulative incidence (NBCCI) (HR=0.484, 95% CI: 0.403-0.583, 95% PI: 0.359-0.654). For adverse events, extended adjuvant endocrine treatment was associated with a significantly higher risk of bone fracture (RR=1.446, 95% CI: 1.208-1.730, 95% PI: 1.154-1.854) and osteoporosis (RR=1.377, 95% CI: 1.018-1.862, 95% PI: 0.347-5.456).

CONCLUSION

Our study showed that extended adjuvant endocrine therapy increased DFS, OS, RFS, DMFS, the incidence of bone fracture and osteoporosis, and reduced NBCCI.

SYSTEMATIC REVIEW REGISTRATION

https://www.crd.york.ac.uk/prospero, identifier (CRD42022351295).

Preventing late recurrence in hormone receptor-positive early breast cancer: a review

Late recurrences are a key challenge for patients with early-stage oestrogen receptor-positive breast cancer, with the risk of disease relapse continuing steadily from 5 to more than 20 years after diagnosis. Five years of adjuvant endocrine therapy with tamoxifen or an aromatase inhibitor was shown many years ago to improve survival. More recently, the trials of extended adjuvant endocrine therapy for more than 5 years have shown a further small gain, but with an associated small risk of increased long-term toxicity including bone loss, cardiovascular impairment and impaired quality of life. This review describes the efficacy and safety of extended endocrine therapy, the optimal selection criteria for patient benefit and the potential for novel agents to improve long-term outcomes.

Endometrial Surveillance in Tamoxifen and Letrozole Treated Breast Cancer Patients

Background: Our study aimed to assess the risk of endometrial pathologies after tamoxifen and aromatase inhibitors (AIs) adjuvant treatment for female breast cancer patients treated at Sultan Qaboos University Hospital in Oman.

Materials and Methods: A total of 457 patients diagnosed with estrogen positive breast cancer between January 2011 and December 2018 were screened. Two hundred and four patients met the inclusion criteria, and their detailed clinicopathological and endometrial surveillance data were collected from their electronic health records.

Results: All patients underwent endometrial assessment during tamoxifen or letrozole therapy. The mean diagnostic age of breast cancer patients is 43.6 years, ranging from 27-84 years. Eighty-three percent of those patients are premenopausal, and 17% are postmenopausal. The mean tamoxifen use duration was 33 months. The majority of patients, 123 (60.3%), have had tamoxifen for three years or less, 47 (23.1%) for 3-5 years, and only 22 (10.8%) were on tamoxifen for more than five years. Increased endometrial thickness was reported in 8% of the premenopausal and 14% of the postmenopausal group. Other endometrial pathologies that were detected are inactive endometrium three (1.47%), atrophic endometrium three (1.47%), serous carcinoma one (0.50%), endometrial cancer two (0.98%), and chronic endometritis one (0.50%), which were not significantly associated with tamoxifen or letrozole therapy duration. Two patients have developed endometrial cancer, and both are postmenopausal and > 60 years old.

Conclusions: Tamoxifen and letrozole did not increase the risk of endometrial cancer in premenopausal patients. Breast Cancer (BC) patients on tamoxifen or letrozole might need a pre-treatment endometrial evaluation and explanation of alarming symptoms to guide further endometrial surveillance.

Positive estrogen receptor status is a poor prognostic factor in node-negative breast cancer: An observational study in Asian patients

This study evaluated the outcomes and prognostic factors for breast cancer according to initial lymph node (LN) status. Among patients with LN-negative breast cancer, we also focused on the prognostic value of estrogen receptor (ER) status.Medical records were retrospectively reviewed for 715 patients who underwent curative surgery for breast cancer between January 2005 and December 2015 at a single Korean institution. We evaluated factors that were associated with metastasis-free survival (MFS) according to LN status.Among the 715 patients (age: 28-87 years), 458 patients (64.1%) did not have axillary LN metastasis. Relative to patients without LN metastasis, patients with LN metastasis had larger tumor sizes and higher histological grades. Among patients with no LN metastasis, ER positivity was associated with non-significantly poorer MFS than ER negativity (mean survival: 138.90 months vs. 146.99 months, p = .17), and patients with LN-negative ER-positive disease had MFS rates of 91.7% at 5 years and 74.5% at 10 years. Among patients with LN-negative ER-positive disease, a poor prognosis was significantly associated with larger tumor size (≥2 cm, P = .03) and older age (≥50 years, P = .03).These results indicate that the risk of metastasis increases over time for patients with LN-negative ER-positive breast cancer, and especially for older patients or patients with larger tumors.

A follow-up study of a randomized controlled study evaluating safety and efficacy of leuprorelin acetate every-3-month depot for 2 versus 3 or more years with tamoxifen for 5 years as adjuvant treatment in premenopausal patients with endocrine-responsive breast cancer

Background

Previously, we conducted the 5-year open-label, randomized controlled trial (RCT) of leuprorelin adjuvant therapy in post-operative premenopausal patients with endocrine-responsive breast cancer, which was a pilot study to investigate the optimal duration of leuprorelin treatment. Since, however, long-term outcomes became required for the adjuvant endocrine therapy, we performed this follow-up observation study.

Methods

Follow-up observation study was performed up to 10th year after randomization, continuing RCT to evaluate the efficacy and safety of leuprorelin every 3 months for ≥ 3 versus 2 years, with daily tamoxifen for 5 years. Primary endpoints were disease-free survival (DFS) and 2-year landmark DFS.

Results

Eligible patients (N = 222) were randomly assigned to receive leuprorelin for either 2 years (N = 112) or ≥ 3 years (N = 110) with tamoxifen. Leuprorelin treatment for ≥ 3 years versus 2 years provided no significant difference in DFS (HR 0.944, 95% CI 0.486–1.8392) or 2-year landmark DFS (N = 99 and 102 in 2-year and ≥ 3-year groups, HR 0.834, 0.397–1.753). In small, higher-risk subgroup (n = 17); however, 2-year landmark DFS in ≥ 3-year group was significantly longer (HR 0.095, 0.011–0.850) than that in 2-year group. The incidence of bone-related adverse events was around 5% in both groups.

Conclusions

Adjuvant leuprorelin treatment for ≥ 3 years with tamoxifen only showed similar efficacy and safety profiles to those for 2 years in analyses among all patients but suggested greater benefit in higher-risk patients. No new safety signal was identified for long-term leuprorelin treatment.

Trial registration number

Not applicable. This was an observational study.

Novel Tamoxifen Nanoformulations for Improving Breast Cancer Treatment: Old Wine in New Bottles

Breast cancer (BC) is one of the leading causes of death from cancer in women; second only to lung cancer. Tamoxifen (TAM) is a hydrophobic anticancer agent and a selective estrogen modulator (SERM), approved by the FDA for hormone therapy of BC. Despite having striking efficacy in BC therapy, concerns regarding the dose-dependent carcinogenicity of TAM still persist, restricting its therapeutic applications. Nanotechnology has emerged as one of the most important strategies to solve the issue of TAM toxicity, owing to the ability of nano-enabled-formulations to deliver smaller concentrations of TAM to cancer cells, over a longer period of time. Various TAM-containing-nanosystems have been successfully fabricated to selectively deliver TAM to specific molecular targets found on tumour membranes, reducing unwanted toxic effects. This review begins with an outline of breast cancer, the current treatment options and a history of how TAM has been used as a combatant of BC. A detailed discussion of various nanoformulation strategies used to deliver lower doses of TAM selectively to breast tumours will then follow. Finally, a commentary on future perspectives of TAM being employed as a targeting vector, to guide the delivery of other therapeutic and diagnostic agents selectively to breast tumours will be presented.

Toronto Workshop on Late Recurrence in Estrogen Receptor-Positive Breast Cancer: Part 1: Late Recurrence: Current Understanding, Clinical Considerations

Disease recurrence (locoregional, distant) exerts a significant clinical impact on the survival of estrogen receptor-positive breast cancer patients. Many of these recurrences occur late, more than 5 years after original diagnosis, and represent a major obstacle to the effective treatment of this disease. Indeed, methods to identify patients at risk of late recurrence and therapeutic strategies designed to avert or treat these recurrences are lacking. Therefore, an international workshop was convened in Toronto, Canada, in February 2018 to review the current understanding of late recurrence and to identify critical issues that require future study. In this article, the major issues surrounding late recurrence are defined and current approaches that may be applicable to this challenge are discussed. Specifically, diagnostic tests with potential utility in late-recurrence prediction are described as well as a variety of patient-related factors that may influence recurrence risk. Clinical and therapeutic approaches are also reviewed, with a focus on patient surveillance and the implementation of extended endocrine therapy in the context of late-recurrence prevention. Understanding and treating late recurrence in estrogen receptor-positive breast cancer is a major unmet clinical need. A concerted effort of basic and clinical research is required to confront late recurrence and improve disease management and patient survival.

The duration of endocrine therapy and breast cancer patients' survival: A nationwide population-based cohort study

As research progressed, the recommended duration of endocrine therapy for breast cancer patients has been extended from 5 to 10 years. This study aimed to investigate how the duration of endocrine medication and therapy affect survival rate in the real world. By using the National Health Insurance Research Database (NHIRD), this study examined 1002 breast cancer patients newly diagnosed between 2000 and 2005 as research subjects, and conducted follow-up until 2013. Among these subjects, 51 used aromatase inhibitors (AIs), 561 used tamoxifen, and 390 alternated between the use of tamoxifen and AIs. The mean follow-up period in this study was 9.63 years, and the mean duration of taking endocrine medication was 4.04 years. The tamoxifen group had the longest follow-up period (9.87 years), shortest endocrine therapy duration (3.29 years), and best survival rate (86.1%). Patients were divided into 3 groups based on the duration of endocrine therapy: under 2 years, 2 to 5 years, and over 5 years. It was found that patients who received medication for less than 2 years showed the lowest survival rate with statistically significant differences (P < .001). Therefore, the extension of endocrine therapy duration is critical in improving breast cancer patients' survival rate.

Considering the biology of late recurrences in selecting patients for extended endocrine therapy in breast cancer

Extended endocrine therapy can reduce recurrences occurring more than 5 years after diagnosis (late recurrences) in estrogen receptor (ER)-positive breast cancer. Given the side effects of endocrine therapy, optimal patient selection for extended treatment is crucial. Enhanced understanding of late recurrence biology could optimize patient selection in this setting. We therefore summarized the current knowledge of late recurrence biology, clinical trials on extended endocrine therapy, and tools for predicting late recurrence and benefit from treatment extension. Extending 5 years of tamoxifen therapy with 5 years of tamoxifen or an aromatase inhibitor (AI) reduces late recurrence risk by 2-5%, but results of extending AI-based therapy are inconsistent. Although several clinicopathological parameters and multigene assays are prognostic for late recurrence, selection tools predicting benefit from extended endocrine therapy are sparse. Therefore, we additionally performed a pooled analysis using 2231 mRNA profiles of patients with ER-positive/human epidermal growth factor receptor 2-negative breast cancer. Gene Set Enrichment Analysis was applied on genes ranked according to their association with early and late recurrence risk. Higher expression of estrogen-responsive genes was associated with a high recurrence risk beyond 5 years after diagnosis when patients had received no systemic therapy. Although 5 years of endocrine therapy reduced this risk, this effect disappeared after treatment cessation. This suggests that late recurrences of tumors with high expression of estrogen-responsive genes are likely ER-driven. Long-term intervention in this pathway by means of extended endocrine therapy might reduce late recurrences in patients with tumors showing high expression of estrogen-responsive genes.

Clinical outcomes comparison of 10 years versus 5 years of adjuvant endocrine therapy in patients with early breast cancer

BACKGROUND

Adjuvant endocrine therapy undoubtedly prolongs the time to recurrence for patients with hormone-positive early breast cancer. Extended endocrine therapy to 10 years or longer has been expected to bring a greater clinical advantage. However, the related research conclusions are controversial.

METHODS

Tamoxifen (TAM), Aromatase Inhibitor (AI), Exemestane, letrozole (LET) and anastrozole were used as key words in the literature search. After the patients completed 5 years of adjuvant endocrine treatment, they were allocated to continue endocrine treatment for 5 years or receive placebo/observation for 5 years. Disease-free survival (DFS) and overall survival (OS) were the end points. Systematic assessment was performed using Stata 12.0.

RESULTS

Twelve trials including 30,848 cases were involved. The overall analysis demonstrated that extended endocrine therapy to 10 years significantly prolonged DFS compared with 5 years of endocrine therapy [hazard ratio (HR) = 0.84, 95% CI: 0.73-0.97]. Subgroup analysis showed that DFS was significant prolonged with TAM 5y - AI 5y treatment versus TAM 5y treatment and with (AI and/or TAM) 5y - LET 5y treatment versus (AI and/or TAM) 5y treatment [(HR = 0.61, 95% CI: 0.50-0.76) and (HR = 0.81, 95% CI: 0.71-0.93), respectively]. However, no significant difference was found in the DFS with TAM 5y - TAM 5y treatment versus TAM 5y treatment (HR = 0.97, 95% CI: 0.81-1.17). Overall and subgroup analysis did not demonstrate an OS benefit of therapy extended to 10 years. A DFS benefit of extended endocrine therapy to 10 years was verified in the lymph node-positive subgroup, postmenopausal subgroup and ER+ and/or PR+ subgroup (HR = 058, 95% CI: 0.45-0.75; HR = 0.70, 95% CI: 0.58-0.80; HR = 0.80, 95% CI: 0.67-0.96).

CONCLUSIONS

An extended 10 years of endocrine treatment yields a DFS benefit for patients with early breast cancer; (AI and/or TAM) 5y - AI 5y treatment is the optimal choice. ER+ and/or PR+, postmenopausal and lymph node-positive patients are the most suitable groups.

Optimizing adjuvant endocrine therapy for early ER+ breast cancer: An update for surgeons

INTRODUCTION

The optimal duration of adjuvant endocrine therapy in early ER + breast cancer has been controversial. This article aims to provide an overview of the evidence.

METHODS

A search of the literature was conducted via MEDLINE using appropriate keywords. Eligible studies were screened and relevant articles were selected for this report.

RESULTS

Studies investigating the role of extended adjuvant tamoxifen beyond 5 years have revealed mixed results depending on the proportion of node positivity. In postmenopausal women, aromatase inhibitors (AIs) for 5 years are superior to tamoxifen. Extending the use of AIs beyond 5 years seem to reduce the risk of relapse in postmenopausal women with node positive disease. The addition of bisphosphonates to counteract AI-related osteopenia may further improve overall and disease-free survival. Women younger than 40 years seem to benefit from ovarian suppression combined with tamoxifen or exemestane.

CONCLUSIONS

An individualised approach is required for every patient. The adverse effects of endocrine therapy should be weighed against the potential benefits of extended therapy to better inform decision-making.

New piperidine derivative DTPEP acts as dual-acting anti-breast cancer agent by targeting ERα and downregulating PI3K/Akt-PKCα leading to caspase-dependent apoptosis

OBJECTIVES

In our ongoing studies to develop ER targeting agents, we screened for dual-acting molecules with a hypothesis that a single molecule can also target both ER positive and negative groups of breast cancer.

MATERIALS AND METHODS

1-(2-(4-(Dibenzo[b,f]thiepin-10-yl)phenoxy)ethyl)piperidine (DTPEP) was synthesized and screened in both MCF-7 (ER+ve) and MDA-MB-231 (ER-ve) cells. Assays for analysis of cell cycle, ROS, apoptosis and MMP loss were carried out using flow cytometry. Its target was investigated using western blot, transactivation assay and RT-PCR. In vivo efficacy of DTPEP was validated in LA-7 syngeneic rat mammary tumour model.

RESULTS

Here, we report identification of dual-acting molecule DTPEP that downregualtes PI3K/Akt and PKCα expression, induces ROS and ROS-dependent apoptosis, loss of mitochondrial membrane potential, induces expression of caspase indicative of both intrinsic and extrinsic apoptosis in MCF-7 and MDA-MB-231 cells. In MCF-7 cells, DTPEP downregulates ERα expression and activation. In MDA-MB-231 cells, primary cellular target of DTPEP is not clearly known, but it downregualtes PI3K/Akt and PKCα expression. In vivo study showed regression of LA-7 syngeneic mammary tumour in SD rat.

CONCLUSIONS

We identified a new dual-acting anti-breast cancer molecules as a proof of concept which is capable of targeting both ER-positive and ER-negative breast cancer.

Meta-analysis of the cumulative risk of endometrial malignancy and systematic review of endometrial surveillance in extended tamoxifen therapy

Background

Optimal management of the endometrium in patients with oestrogen receptor-positive breast cancer taking extended tamoxifen therapy (for 10 years) remains uncertain. A meta-analysis was performed to determine the cumulative risk ratio (RR) for endometrial malignancy following extended compared with standard tamoxifen treatment. A systematic review was undertaken to identify whether routine endometrial surveillance in patients receiving tamoxifen is associated with earlier detection and reduced incidence of endometrial malignancy.

Methods

Two independent searches were undertaken in the Cochrane Library, PubMed and MEDLINE. A meta-analysis was performed of RCTs reporting on endometrial malignancy risk in extended tamoxifen therapy. A systematic review included prospective studies investigating the benefit of endometrial surveillance during tamoxifen therapy.

Results

Four RCTs reported on endometrial risk in extended tamoxifen therapy. The cumulative risk of endometrial malignancy increased twofold from 1·5 to 3·2 per cent with extended therapy compared with the standard 5 years of tamoxifen (RR 2·29, 95 per cent c.i. 1·60 to 3·28; P &lt; 0·001). Four studies analysed the value of endometrial screening in 5-year cohorts. Endometrial cancer rates of up to 2 per cent were reported, which is higher than rates in the large extended tamoxifen trials.

Conclusion

Extended adjuvant tamoxifen is associated with an increase in endometrial cancer. No clear benefit has been shown for routine endometrial surveillance in asymptomatic patients on tamoxifen therapy.

Optimal management of luminal breast cancer: how much endocrine therapy is long enough?

Patients with early estrogen receptor-positive breast cancer are at continuous risk of relapse even after more than 10 years of follow up. Currently, no biomarker that identifies patients for early versus late recurrence, or one that selects patients or tumors for longer versus shorter durations of endocrine therapy (ET) is available and a crucial question is how to properly select patients who could be spared extended ET or those who require it. In the last 20 years more than 40,000 women were enrolled in randomized trials to answer the question of optimal duration of ET. According to the results of these studies extended adjuvant ET is more effective than standard 5 years of adjuvant ET. Extended ET in patients who remain premenopausal after 5 years of adjuvant tamoxifen is still tamoxifen for another 5 years. Extended ET with aromatase inhibitors (AIs) should be offered to postmenopausal women with substantial residual risk of relapse after completing 5 years of tamoxifen therapy. Extension of AI treatment to 10 years resulted in significantly better 5-year disease-free survival including disease recurrence local/distant or the occurrence of contralateral breast cancer events. Currently, new therapeutic targets are under investigation, but the beneficial effect of prolonged treatment for high-risk patients, identified by using multigenomic tests, remains unclear. Thus, further studies need to be performed to confirm the advantage of extended adjuvant ET in selected patients.

Current Status of Extended Adjuvant Endocrine Therapy in Early Stage Breast Cancer

OPINION STATEMENT

In the past decade, several endocrine treatment regimens have been developed for the adjuvant treatment of postmenopausal women with hormone receptor-positive early breast cancer, including tamoxifen, aromatase inhibitors (AI), or a combination of these. The standard duration of adjuvant endocrine treatment has been 5 years for a long time. Nevertheless, the high number of recurrences occurring after 5 years suggested that extended endocrine therapy could further improve outcome, which led to the start of several randomized clinical trials investigating the effects of extended use of endocrine therapy. The extended duration of tamoxifen has been shown to improve disease-free survival and overall survival in the ATLAS and aTTom trials. However, in postmenopausal women, AIs have been shown to be more effective when compared with tamoxifen. Based hereon, it is recommended that adjuvant endocrine therapy in postmenopausal women with early breast cancer should include an AI. Recently, the DATA, IDEAL, and NSABP B42 trials showed that extended adjuvant endocrine therapy with AIs beyond 5 years in postmenopausal women with early breast cancer did reduce the occurrence of secondary breast tumors, but had no or only a small impact on distant metastasis free survival. Furthermore, toxicity of adjuvant AIs led to gradually decreasing compliance rates and long-term toxicities to non-breast cancer-related deaths. Therefore, we suggest considering extended adjuvant treatment only in women with high-risk early breast cancer who tolerate treatment well.

Two years of tamoxifen or no adjuvant systemic therapy for patients with high-risk breast cancer: long-term follow-up of the Copenhagen breast cancer trial

BACKGROUND

The Copenhagen Breast Cancer Trial (CBCT) randomly assigned patients with early breast cancer to two years of tamoxifen or placebo and we evaluated the effect over the following four decades.

PATIENT AND METHODS

Between 1975 and 1978, 327 patients with primary breast cancer were randomly assigned to two years of daily placebo or tamoxifen. Survival statistics was collected from the Danish Civil Registration System.

RESULTS

The five-year invasive breast cancer recurrence (BCR) rate was 43.2% in the placebo arm and 31.9% in the tamoxifen arm. Compared with the placebo arm the hazard ratio for a BCR event was 0.73 in the tamoxifen arm (p = .07). With an estimated median follow-up on overall survival of 40.9 years, 154 and 145 patients had died in the placebo and tamoxifen arm, respectively. After adjustment for baseline characteristics a significant reduction in mortality was obtained from tamoxifen (HR 0.79; p = .04).

CONCLUSION

Two years of adjuvant tamoxifen resulted in a sustained reduction in mortality in pre- and postmenopausal high-risk breast cancer patients with long-term follow-up data.

Cardiotoxicity of aromatase inhibitors and tamoxifen in postmenopausal women with breast cancer: a systematic review and meta-analysis of randomized controlled trials

Background

Aromatase inhibitors (AIs) have been associated with cardiovascular disease in adjuvant randomized controlled trials (RCTs) comparing these drugs to tamoxifen. However, it is unclear whether this risk is real or due to cardioprotective effects of tamoxifen. To address this question, we conducted a systematic review and meta-analysis of all RCTs of AIs and tamoxifen in adjuvant and extended adjuvant setting.

Patients and methods

We searched PubMed, Embase (OVID), Cochrane CENTRAL, WHO International Clinical Trials Registry Platform, and ClinicalTrials.gov from inception to June 2016 for all RCTs comparing cardiovascular and cerebrovascular safety of AIs to tamoxifen, AIs to placebo or no-treatment, or tamoxifen to placebo or no-treatment in the adjuvant or extended adjuvant setting. Relative risks (RRs) were pooled using DerSimonian and Laird random-effects models with analyses stratified by RCT design.

Results

A total of 19 RCTs were included in the meta-analysis (n  =  62 345). In the adjuvant setting, AIs were associated with a 19% (RR: 1.19, 95% confidence interval [CI]: 1.07-1.34) increased risk of cardiovascular events compared with tamoxifen. AIs were not associated with an increased risk compared with placebo in the extended-adjuvant setting (RR: 1.01, 95% CI: 0.85-1.20). In the adjuvant setting, tamoxifen was associated with a 33% (RR: 0.67, 95% CI: 0.45-0.98) decreased risk compared with placebo or no-treatment. The results from extended adjuvant RCTs comparing tamoxifen to placebo were inconclusive but suggestive of a small protective effect (RR: 0.91, 95% CI: 0.77-1.07).

Conclusions

The increased risk of cardiovascular events with AIs relative to tamoxifen is likely the result of cardioprotective effects of the latter. This new evidence should be considered when assessing the benefits and risks of AIs in the treatment of breast cancer.

Extended Adjuvant Endocrine Therapy in Hormone Receptor-Positive Early Breast Cancer

Despite meaningful, incremental improvements in detection, local treatment and adjuvant systemic treatments for breast cancer, there remains a significant risk of late relapse in hormone receptor (HR)-positive disease. 5 years of tamoxifen or an aromatase inhibitor for all patients with HR-positive early breast cancer is considered standard; however, there are now data to support an extended approach using up to 10 years of treatment. This review will provide some historical background on endocrine therapy and summarize the key clinical trials that demonstrate the small absolute benefit of extended adjuvant therapy. We provide suggested treatment algorithms for both premenopausal and postmenopausal patients and an overview of ongoing adjuvant trials.

Which women decide to take tamoxifen?

PURPOSE

To identify factors which predict, among estrogen receptor (ER)-positive breast cancer patients, who chooses to take adjuvant tamoxifen.

METHODS

We studied 1347 women with ER-positive breast cancer who were treated at Women's College Hospital between 1987 and 2000. For each patient, we obtained information on age at diagnosis, tumour size, lymph node status, ER status, treatments received and dates of local recurrence and of death. We compared women who did and who did not take tamoxifen for a range of factors. We used the Kaplan-Meier method to estimate 15-year local recurrence-free and breast cancer-specific survival rates for women who did and who did not take tamoxifen.

RESULTS

Overall, 50.4% of women who had a mastectomy took tamoxifen and 61.0% of women who had a lumpectomy took tamoxifen (p = 0.002). Tamoxifen use did not correlate with any of the factors that were predictive of a high risk of death from breast cancer, such as young age, large tumour size and positive lymph node status. Young women (<40 years) experienced much higher mortality (41.1%) than older (>60 years) women (14.1%, p < 0.01), but were much less likely to have taken tamoxifen (35.0 vs. 74.6%, p < 0.01).

CONCLUSIONS

Approximately one-half of women with ER-positive breast cancer who are candidates for tamoxifen did not take tamoxifen. Women with lumpectomy were more likely to take tamoxifen than women with mastectomy. Paradoxically, women at high risk of death from breast cancer (less than 40 at diagnosis and/or lymph node positive) and who are expected to receive the greatest benefit from tamoxifen in terms of mortality reduction were less likely to take it than were low-risk women (older women, lymph node negative). These findings suggest that women consider the reduction in risk from local recurrence to be more important than the reduction in risk of death from breast cancer when they consider taking tamoxifen.

Extended Adjuvant Endocrine Therapy in Breast Cancer: Evidence and Update - A Review

The optimal duration and treatment strategies involving adjuvant endocrine therapy in early breast cancer remained largely undetermined. As data emerge on the various modalities of treatment in both pre- and postmenopausal groups, debates, and discussions continue. Most studies to date focused on the 5-year duration of treatment consisting of mainly tamoxifen. The Arimidex, Tamoxifen, Alone or in Combination (ATAC) study demonstrated that anastrozole is superior to tamoxifen and has become the mainstream treatment in postmenopausal women with early breast cancer, although the duration was arbitrarily set for 5 years, analogous to tamoxifen treatment. Several clinical trials, however, have emerged to support extended endocrine therapy as it becomes clear that the recurrence risk of breast cancer does not decrease beyond the initial 5 years of treatment. The advent of molecular signatures also plays an important role in the breast cancer profiling, and where available should be incorporated in the overall decision-making. Furthermore, side effects and noncompliance pose another issue in achieving an optimal treatment benefit. The decision-making as regards to extended endocrine treatment should therefore focus not only on the cancer biology alone but also include treatment side effects, assessment of risk of recurrence and patients' preference. In this review, we present an overview of the published studies to date as well as ongoing studies on the topic to better refine the options for adjuvant hormonal therapy.

Extended adjuvant endocrine therapy - A standard to all or some?

Patients with estrogen receptor-positive (ER +) early breast cancer (EBC) are at a continuous risk for distant relapse despite 5 years of standard endocrine therapy, even after 10-15 years after primary diagnosis. Hence, large randomized clinical trials were conducted to evaluate the role of extended endocrine treatment (ET) with the primary goal to prevent or at least delay distant relapse. Two very large trials of extended tamoxifen (TAM), the ATLAS and the aTTom trial, proved the efficacy of prolonged TAM particularly important after 10 years due to the carry-over effect of the five initial years. Additionally, the extended use of AIs after 5 years of tamoxifen, also proved to be efficacious in preventing late distant relapses. For letrozole (LET) it was shown in the MA.17 trial that it also improves overall survival (OS) in node-positive BC patients. There are many options and still unanswered questions related to extended ET, which are discussed in this review. The most important issue in deciding prolonged duration of ET is undoubtfully how to identify ER+ patients who benefit most from this approach. With this purpose, not only classical pathological factors have been studied, but also molecular profiles of individual tumors, which might help us in the near future to better tailor ET. Not only efficacy, but also toxicity of such prolonged treatment is essential for optimal use, particularly maintained compliance in a routine clinical practice. These issues are discussed in this review.

Adjuvant endocrine therapy for premenopausal women with hormone-responsive breast cancer

Multiple strategies for endocrine treatment of premenopausal women with hormone-responsive breast cancer have been assessed and results have been presented over the last two years. These include tamoxifen for 5-10 years (ATLAS and aTTom), tamoxifen for 5 years followed by aromatase inhibitor (AI) for 5 years for women who have become postmenopausal (MA-17); ovarian ablation (OA) by surgery (EBCTCG overview); ovarian function suppression (OFS) by LHRH agonist (LHRH agonist meta-analysis); or combinations of approaches including OFS plus tamoxifen or AI (SOFT, TEXT, ABCSG 12 and E3193). Many of these trials have taken place in the backdrop of (neo)adjuvant chemotherapy which can confound interpretation because such therapy can suppress ovarian function either transiently or permanently. Nonetheless these trials suggest in aggregate that 10 years of tamoxifen are better than 5 years and that a program of extended adjuvant therapy of tamoxifen for 5 years followed by aromatase inhibitor for 5 years is effective for suitable candidates. The SOFT and E3193 trials do not show a major advantage for use of OFS + tamoxifen compared to tamoxifen alone. The joint SOFT/TEXT analysis and ABCGS12 trials both suggest that outcomes can be excellent with the use of combined endocrine therapy alone in properly selected patients but give conflicting results with regard to potential benefits for OFS + AI compared with OFS + tamoxifen. Further work will be needed to ascertain long-term outcomes, identify factors that predict who will benefit from extended adjuvant endocrine therapy, and assess role of OFS by medical or surgical means. It is clear, however, that endocrine therapy is a critical part of the adjuvant regimen for most premenopausal women with hormone-responsive breast cancer, and a subset of these women with luminal A-type tumors can be safely treated with endocrine therapy alone.

Factors associated with late recurrence after completion of 5-year adjuvant tamoxifen in estrogen receptor positive breast cancer

BACKGROUND

Recent large trials have shown the survival benefits of 10-year use of tamoxifen by reducing late recurrence compared with 5-year therapy in estrogen receptor(ER)-positive breast cancer. We tried to identify clinical factors associated with the late recurrence.

METHODS

We reviewed our database of ER-positive patients who had received operations between 1996 and 2006 in two institutions. We selected 444 who had completed 5-year tamoxifen and were disease-free up to 10 years after the operation. Patients who had received aromatase inhibitors with any regimens were excluded. As a late recurrence group, 139 patients were identified who had completed 5-year tamoxifen, but had recurrence afterwards. Among them, 61 had local/contralateral breast recurrence and 78 had distant metastasis. The median follow-up was 9.7 years. Clinicopathological factors at the time of initial operation, such as age, menopausal status, progesterone receptor expression, HER2 status, tumor grade and Ki-67, were compared between the disease-free group and the late recurrence group.

RESULTS

In a univariate analysis, tumor size (>2 cm), lymph node metastasis and high histologic grade were significantly associated with late recurrences (p < 0.05). In a multivariate analysis, only axillary lymph node metastasis was significant (p < 0.001). Late distant metastasis was significantly associated with tumor size and axillary lymph node metastasis (p = 0.038, p < 0.001,respectively). Late local/contralateral breast recurrence was associated with axillary lymph node metastasis (p = 0.042).

CONCLUSIONS

Our data showed axillary lymph node metastasis at initial operation was the only risk factor of late recurrence after completion of tamoxifen for 5 years. Our results can be helpful in making decisions to use extended tamoxifen beyond 5 years.

Structural and functional characterization of aromatase, estrogen receptor, and their genes in endocrine-responsive and -resistant breast cancer cells

Aromatase and estrogen receptor α (ER) are two key proteins for the proliferation of endocrine-responsive and -resistant breast cancers. Aromatase is an enzyme involved in the conversion of androgen (such as testosterone) to estrogen (such as 17β-estradiol). It is also a very effective therapeutic target for the treatment of endocrine-responsive breast cancer. Comparing endocrine-responsive and -resistant breast cancer, aromatase protein levels do not change significantly. Aromatase activity; however, can be increased via PI3K/Akt/IGFR signaling pathways in endocrine resistant cells. The activity of aromatase has been reported to be modulated by phosphorylation. The ER is an important steroid nuclear receptor in the proliferation of both endocrine-responsive and -resistant cells. Although the mutation or amplification of ER can cause endocrine resistance, it is not commonly found. Some point mutations and translocation events have been characterized and shown to promote estrogen-independent growth. Phosphorylation by cross-talk with growth factor pathways is one of the main mechanisms for ligand-independent activation of ER. Taken together, both ER and aromatase are important in ER-dependent breast cancer and the development of endocrine resistance.

A randomized controlled study evaluating safety and efficacy of leuprorelin acetate every-3-months depot for 2 versus 3 or more years with tamoxifen for 5 years as adjuvant treatment in premenopausal patients with endocrine-responsive breast cancer

BACKGROUND

Luteinizing hormone-releasing hormone (LH-RH) agonists provide effective adjuvant treatment for premenopausal women with endocrine-responsive breast cancer. Here, we investigated appropriate treatment durations of an LH-RH agonist, leuprorelin.

METHODS

We conducted an open-label, randomized controlled pilot study to evaluate the safety and efficacy of leuprorelin subcutaneously administered every-3-months for 2 versus 3 or more, up to 5 years, together with daily tamoxifen for 5 years in premenopausal endocrine-responsive breast cancer patients. Primary endpoints were disease-free survival (DFS) and safety.

RESULTS

Eligible patients (N = 222) were randomly assigned to receive leuprorelin for either 2 years (N = 112) or 3 or more years (N = 110) with tamoxifen for 5 years after surgery. Leuprorelin treatment for 3 or more years provided no significant difference in DFS rate over 2 years: 94.1 versus 91.8 % at 144 weeks (3 years) after the second year (week 96) and 90.8 versus 90.4 % at the fifth year (week 240). The overall survival rate was 100 % for both groups during the third through fifth year study period. There were no significant differences in the incidence of adverse events (AEs) between the 2 groups: most AEs were rated grade 1 or 2.

CONCLUSIONS

Adjuvant leuprorelin treatment for 3 or more years with tamoxifen showed a survival benefit and safety profile similar to that for 2 years in premenopausal endocrine-responsive breast cancer patients. No new safety signal was identified for long-term leuprorelin treatment. Longer follow-up observation is needed to determine the optimal duration of leuprorelin treatment.

Update in treatment of early breast cancer in post-menopausal women

In the last few years there have been significant advances in knowledge related to the treatment of post-menopausal women with early stage breast cancer. These include new information about the survival benefits with hormonal therapies and bone targeted treatments as well as identification of patient populations who may be able to avoid toxic treatments. In this paper we discuss these advances and provide suggested management algorithms.

Endocrine therapy in premenopausal women with breast cancer: a critical appraisal of current evidence

Nearly 60% of all breast cancer premenopausal women are diagnosed with a hormone receptor positive tumor and, therefore, are candidates for adjuvant hormonal therapy. Treatment with tamoxifen for at least 5 years has been for a long time the standard of care, as it is associated with overall positive clinical outcomes. However, in the last decade, a number of studies on adjuvant endocrine therapy in premenopausal women with hormone receptor positive breast cancer have been published, adding a bulk of evidence to existing knowledge in this field. A critical appraisal of their results appears necessary in order to put the recently collected data into the current framework of treatment, and to discuss the several issues that remain open. Here, we review the most recent evidence on the following: the optimal duration of tamoxifen treatment, results of the studies comparing tamoxifen alone to tamoxifen plus ovarian function suppression (OFS), results of the studies comparing tamoxifen plus OFS to aromatase inhibitors plus OFS.

The UZ Leuven Policy for Extended Adjuvant Anti-estrogen Therapy in Women With Early Estrogen Receptor-Positive Breast Cancer

Opinion statement: Five years after adjuvant endocrine treatment for estrogen receptor (ER)-positive breast cancer, patients have a 2 to 20 % risk of metastatic relapse during the next 5 years. Extended adjuvant endocrine therapy seems to further lower this. In UZ Leuven, extended endocrine therapy is now discussed unless the tumor was a grade 1-2, pT1N0, ER-positive, progesterone receptor (PR)-positive, HER2-negative lesion. After 5 years of adjuvant tamoxifen treatment for ER-positive breast cancer, we encourage women to take another 5 years of tamoxifen. If the tumor was lymph node-positive at diagnosis and patients are menopausal after the first 5 years of tamoxifen, we advise to take prolonged treatment with an oral aromatase inhibitor (AI). For this particular group, available data for extending endocrine therapy with an AI after 5 years of tamoxifen are strongest and more convincing for letrozole than for anastrozole or exemestane. Under these conditions, letrozole is reimbursed for 3 years in Belgium. If women are postmenopausal at diagnosis and already used an oral AI at any time during the first 5 years, we discuss an extra 5 years of tamoxifen. Results from ongoing clinical trials will tell us whether in these cases prolonged AI use is better than tamoxifen so that therapy can be adapted. Benefit from extended adjuvant endocrine therapy is likely larger with better compliance and potential side effects of extended endocrine therapy need to be discussed. Therefore, when advising extended adjuvant endocrine treatment, a balance should always be made between relapse risk and treatment tolerance/compliance.

Clinical utility of exemestane in the treatment of breast cancer

Breast cancer is the most prevalent cancer in women, causing a significant mortality worldwide. Different endocrine strategies are available for the treatment of hormone-sensitive breast cancer, including antiestrogen tamoxifen and fulvestrant, as well as third-generation aromatase inhibitors (AIs), such as letrozole, anastrozole, and exemestane. In this review, we will focus on exemestane, its clinical use, and its side effects. Exemestane is a steroidal third-generation AI now used in all treatment settings for breast cancer. In the metastatic disease, it has been extensively investigated as the first-, second-, and further-line treatment and it is now registered for the treatment of postmenopausal women with advanced estrogen-receptor-positive breast cancer whose disease has progressed following antiestrogen therapy. A potential lack of cross-resistance with nonsteroidal AIs has been described, giving additional therapeutic opportunities in sequences of endocrine agents. Exemestane is also approved for the adjuvant treatment of postmenopausal early breast cancer, either as upfront monotherapy for 5 years, as a switch following 2–3 years of tamoxifen, or as extended therapy beyond 5 years of adjuvant treatment. New promising data also showed a beneficial effect in young premenopausal early breast cancer patients, when administered together with ovarian suppression. Interesting results have also emerged when exemestane has been investigated as neodjuvant treatment as well as preventive agent in healthy women at high risk for breast cancer. Exemestane is generally well tolerated, with a side effect profile similar to that of other AIs, including menopausal symptoms, arthralgia, and bone loss. In conclusion, exemestane can be considered an effective and well-tolerated endocrine treatment option for all stages of breast cancer.

Adjuvant endocrine therapy for early breast cancer: a systematic review of the evidence for the 2014 Cancer Care Ontario systemic therapy guideline

BACKGROUND

Cancer Care Ontario's Program in Evidence-Based Care (pebc) recently created an evidence-based consensus guideline on the systemic treatment of early breast cancer. The evidence for the guideline was compiled using a systematic review to answer the question "What is the optimal systemic therapy for patients with early-stage, operable breast cancer, when patient and disease factors are considered?" The question was addressed in three parts: cytotoxic chemotherapy, endocrine treatment, and her2 (human epidermal growth factor receptor 2)-targeted therapy.

METHODS

For the systematic review, the literature in the medline and embase databases was searched for the period January 2008 to May 2014. The Standards and Guidelines Evidence directory of cancer guidelines and the Web sites of major oncology guideline organizations were also searched. The basic search terms were "breast cancer" and "systemic therapy" (chemotherapy, endocrine therapy, targeted agents, ovarian suppression), and results were limited to randomized controlled trials (rcts), guidelines, systematic reviews, and meta-analyses.

RESULTS

Several hundred documents that met the inclusion criteria were retrieved. Meta-analyses from the Early Breast Cancer Trialists' Collaborative Group encompassed many of the rcts found. Several additional studies that met the inclusion criteria were retained, as were other guidelines and systematic reviews.

SUMMARY

The results of the systematic review constitute a comprehensive compilation of high-level evidence, which was the basis for the 2014 pebc guideline on systemic therapy for early breast cancer. The review of the evidence for systemic endocrine therapy (adjuvant tamoxifen, aromatase inhibitors, and ovarian ablation and suppression) is presented here; the evidence for chemotherapy and her2-targeted treatment-and the final clinical practice recommendations-are presented separately in this supplement.

Extended adjuvant endocrine therapy in hormone-receptor positive breast cancer

A high ongoing recurrence rate in patients with endocrine responsive breast cancer provides the rationale for offering endocrine treatment for more than five years. The MA.17 study, comparing the aromatase inhibitor (AI) letrozole for five years after an initial five years of tamoxifen to no further treatment, provided the proof-of-principle for extended endocrine treatment. These results have meanwhile been confirmed by several other studies and an EBCTCG meta-analysis. More recently, data from the ATLAS trial, comparing 10 to five years of tamoxifen, have been published, similarly showing a benefit for longer endocrine treatment with tamoxifen. In postmenopausal women -including those who had been premenopausal at initial diagnosis - a cross-trial comparison of ATLAS and the AI studies indicates superiority of switching to letrozole versus ongoing tamoxifen, similar to superiority of the AIs over tamoxifen in the metastatic and early breast cancer settings.

Adjuvant endocrine therapy for women with hormone receptor-positive breast cancer: american society of clinical oncology clinical practice guideline focused update

PURPOSE

To update the ASCO clinical practice guideline on adjuvant endocrine therapy on the basis of emerging data on the optimal duration of treatment, particularly adjuvant tamoxifen.

METHODS

ASCO convened the Update Committee and conducted a systematic review of randomized clinical trials from January 2009 to June 2013 and analyzed three historical trials. Guideline recommendations were based on the Update Committee's review of the evidence. Outcomes of interest included survival, disease recurrence, and adverse events.

RESULTS

This guideline update reflects emerging data on duration of tamoxifen treatment. There have been five studies of tamoxifen treatment beyond 5 years of therapy. The two largest studies with longest reported follow-up show a breast cancer survival advantage with 10-year durations of tamoxifen use. In addition to modest gains in survival, extended therapy with tamoxifen for 10 years compared with 5 years was associated with lower risks of breast cancer recurrence and contralateral breast cancer.

RECOMMENDATIONS

Previous ASCO guidelines recommended treatment of women who have hormone receptor-positive breast cancer and are premenopausal with 5 years of tamoxifen, and those who are postmenopausal a minimum of 5 years of adjuvant therapy with an aromatase inhibitor or tamoxifen followed by an aromatase inhibitor (in sequence). If women are pre- or perimenopausal and have received 5 years of adjuvant tamoxifen, they should be offered 10 years total duration of tamoxifen. If women are postmenopausal and have received 5 years of adjuvant tamoxifen, they should be offered the choice of continuing tamoxifen or switching to an aromatase inhibitor for 10 years total adjuvant endocrine therapy.

Extended adjuvant tamoxifen for early breast cancer: a meta-analysis

Background

Hormone receptor positive breast cancer is characterized by the potential for disease recurrence many years after initial diagnosis. Endocrine therapy has been shown to reduce the risk of such recurrence, but the optimal duration of endocrine therapy remains unclear.

Methods

We conducted a systematic review and meta-analysis to quantify the benefits and harms of extended adjuvant tamoxifen (>5 years of therapy) compared with adjuvant tamoxifen (5 years of therapy). Odds ratios (ORs) and 95% confidence intervals (CIs) were computed for disease recurrence, death and adverse events. Subgroup analyses by timing of recurrence and baseline lymph node and menopause status were carried.

Results

Five trials comprising 21,554 patients were included. Extended adjuvant tamoxifen was not associated with a significant reduction in the risk of recurrence (OR:0.89, 95% CI 0.76–1.05, p = 0.17). There was no association between extended adjuvant tamoxifen and all-cause death (OR:0.99, 95% CI 0.84–1.16, p = 0.88). There was an apparent reduction in risk of recurrence occurring after completion of extended adjuvant tamoxifen with little evidence of effect during therapy, however, this difference was not significant (p for difference 0.10). Subgroup analysis suggested that a greater effect size among lymph node positive patients compared with those who are lymph node negative (NNT: 25 vs. 49). There was no apparent difference in the effect between pre- and post-menopausal patients. Endometrial carcinoma was substantially more frequent with extended adjuvant tamoxifen (OR:2.06, 95% CI 1.65–2.58, p<0.001, number needed to harm:89).

Conclusion

In unselected patients, extended adjuvant tamoxifen is not associated with a significant reduction in recurrence, or a reduction in all-cause death. Patients with lymph node positive breast cancer may derive some benefit. Reduction in the risk of recurrence appears to occur only after completion of extended adjuvant therapy.

Aromatase inhibition 2013: clinical state of the art and questions that remain to be solved

Following their successful implementation for the treatment of metastatic breast cancer, the 'third-generation' aromatase inhibitors (anastrozole, letrozole, and exemestane) have now become standard adjuvant endocrine treatment for postmenopausal estrogen receptor-positive breast cancers. These drugs are characterized by potent aromatase inhibition, causing >98% inhibition of estrogen synthesis in vivo. A recent meta-analysis found no difference in anti-tumor efficacy between these three compounds. As of today, aromatase inhibitor monotherapy and sequential treatment using tamoxifen followed by an aromatase inhibitor for a total of 5 years are considered equipotent treatment options. However, current trials are addressing the potential benefit of extending treatment duration beyond 5 years. Regarding side effects, aromatase inhibitors are not found associated with enhanced risk of cardiovascular disease, and enhanced bone loss is prevented by adding bisphosphonates in concert for those at danger of developing osteoporosis. However, arthralgia and carpal tunnel syndrome preclude drug administration among a few patients. While recent findings have questioned the use of aromatase inhibitors among overweight and, in particular, obese patients, this problem seems to focus on premenopausal patients treated with an aromatase inhibitor and an LH-RH analog in concert, questioning the efficacy of LH-RH analogs rather than aromatase inhibitors among overweight patients. Finally, recent findings revealing a benefit from adding the mTOR inhibitor everolimus to endocrine treatment indicate targeted therapy against defined growth factor pathways to be a way forward, by reversing acquired resistance to endocrine therapy.

Five or more years of adjuvant endocrine therapy in breast cancer: a meta-analysis of published randomised trials

Five years of adjuvant hormonal therapy is the standard of care in early breast cancer (BC) expressing oestrogen receptors (ER+). Prolonged duration of adjuvant endocrine therapy is implemented to prevent recurrence and death; in particular, its carryover effect may prevent very late events. This meta-analysis compares the efficacy of 5 years of hormonal therapy alone with that of additional years of hormonal therapy, in patients with early BC. Randomised trials comparing 5 years versus more than 5 years of hormonal therapy in BC were identified by electronic searches of PubMed, EMBASE, ISI Web of Science and the Cochrane Central Register of Controlled Trials. Meta-analysis was performed using the fixed- or random-effects models. The primary endpoints were overall survival (OS), BC-specific survival (BCSS) and relapse-free survival (RFS) reported as odds ratios (ORs) and 95 % confidence interval (CI). Eight trials, including 29,138 patients, were identified. Overall, in ER+ BCs, extended endocrine therapy beyond 5 years of tamoxifen significantly improved OS (OR, 0.89; 95 % CI 0.80-0.99; P = 0.03), BCSS (OR, 0.78; 95 % CI 0.69-0.9; P = 0.0003) and RFS (OR 0.72; 95 % CI 0.56-0.92; P = 0.01) compared with 5 years of hormonal therapy alone. Loco-regional and distant relapses were reduced by 36 and 13 %, respectively. Compared with 5 years of tamoxifen, additional adjuvant endocrine therapy reduced risk of death and relapse of ER+ BC by ~10 and 30 %, respectively. This strategy should be considered in patients free of disease after 5 years of hormonal therapy.

Hazard of breast cancer-specific mortality among women with estrogen receptor-positive breast cancer after five years from diagnosis: implication for extended endocrine therapy

PURPOSE

More than half of the patients with estrogen receptor (ER)-positive breast cancers will relapse and die from breast cancer at 5-10 yr after diagnosis despite 5-yr endocrine therapy. Subpopulations of ER-positive patients at high risk of breast cancer-specific mortality (BCSM) at 5-10 yr are undetermined.

METHODS

Using the Surveillance, Epidemiology, and End-Results program (1990-2003), we analyzed the relative hazard ratio (HR) and absolute HR of BCSM and the cumulative 10-yr breast cancer-specific survival (BCSS) in 111,993 breast cancer patients, stratified by ER, age, and lymph node (LN), and adjusted for other prognostic factors.

RESULTS

At 5-10 yr after diagnosis, ER-positive patients had increased risk of BCSM [HR, 0.71; 95% confidence interval (CI), 0.66-0.76; ER-positive as reference] compared with ER-negative patients. Specifically, younger ER-positive patients (<40 yr) had a constant plateau of annual hazard rate, a higher hazard of BCSM (HR, 0.43; 95% CI, 0.35-0.52; ER-positive as reference), and poor 10-yr BCSS, despite LN status. Among ER-positive patients aged 40-60 yr having no obvious plateau of hazard rate, only those with LN-positive disease had a significantly increased hazard of BCSM and poor 10-yr BCSS. Elderly ER-positive patients aged 60-74 yr had a hazard of BCSM, similar to that of ER-negative patients, and those with LN-positive disease had poor 10-yr BCSS.

CONCLUSION

Our findings help to define the ER-positive subpopulations at higher risk of BCSM at 5-10 yr after diagnosis and are useful in choosing candidates for clinical trials of extended endocrine therapy after 5-yr treatment and in guiding individualized treatment.

The development of endocrine therapy for women with breast cancer

The development of endocrine therapies has transformed the treatment of patients with breast cancer. The shift from ablative surgery and aggressive chemotherapies to more targeted, better tolerated therapy has improved both mortality and quality of life for patients with hormone-responsive disease. During the 1970s, the selective oestrogen-receptor modulator, tamoxifen, emerged as a new treatment for women with advanced breast cancer. The subsequent development of numerous and diverse selective endocrine therapies such as luteinising hormone-releasing hormone agonists, aromatase inhibitors and oestrogen-receptor antagonists have added further treatment options. Furthermore, with well-tolerated and effective endocrine therapy, adjuvant treatment became an option for patients with early breast cancer. Tamoxifen emerged as the gold standard adjuvant therapy in the 1980s; however, later trials in postmenopausal women showed the aromatase inhibitors offer advantages over tamoxifen. In addition to AIs being indicated as adjuvant therapy, some are also being evaluated for use as a preventative measure in high-risk women. This chronological account outlines key milestones in the evolution of endocrine therapies over the last 40 years, highlighting each class of agent and the key trials that have led to changes in clinical practice. The advances in endocrine therapies outlined here, coupled with advances in breast cancer management and diagnostics, will likely lead to more patient-tailored therapy, resulting in greater clinical benefits and more cost-effective treatment strategies.

Hormonal therapy in breast cancer: a model disease for the personalization of cancer care

The treatment of breast cancer is driven by subtype classification, of which the assessment of hormone receptor status is one of the important determinants of therapy. The use of hormonal therapy to treat estrogen-receptor positive breast cancer has been studied for over a century and is one of the well-described uses of personalized medicine. In this review, we will describe the classification of hormone receptor status and the various endocrine treatment strategies. Opportunities for personalization of care are illustrated.

Relevance of breast cancer hormone receptors and other factors to the efficacy of adjuvant tamoxifen: patient-level meta-analysis of randomised trials

BACKGROUND

As trials of 5 years of tamoxifen in early breast cancer mature, the relevance of hormone receptor measurements (and other patient characteristics) to long-term outcome can be assessed increasingly reliably. We report updated meta-analyses of the trials of 5 years of adjuvant tamoxifen.

METHODS

We undertook a collaborative meta-analysis of individual patient data from 20 trials (n=21,457) in early breast cancer of about 5 years of tamoxifen versus no adjuvant tamoxifen, with about 80% compliance. Recurrence and death rate ratios (RRs) were from log-rank analyses by allocated treatment.

FINDINGS

In oestrogen receptor (ER)-positive disease (n=10,645), allocation to about 5 years of tamoxifen substantially reduced recurrence rates throughout the first 10 years (RR 0·53 [SE 0·03] during years 0-4 and RR 0·68 [0·06] during years 5-9 [both 2p<0·00001]; but RR 0·97 [0·10] during years 10-14, suggesting no further gain or loss after year 10). Even in marginally ER-positive disease (10-19 fmol/mg cytosol protein) the recurrence reduction was substantial (RR 0·67 [0·08]). In ER-positive disease, the RR was approximately independent of progesterone receptor status (or level), age, nodal status, or use of chemotherapy. Breast cancer mortality was reduced by about a third throughout the first 15 years (RR 0·71 [0·05] during years 0-4, 0·66 [0·05] during years 5-9, and 0·68 [0·08] during years 10-14; p<0·0001 for extra mortality reduction during each separate time period). Overall non-breast-cancer mortality was little affected, despite small absolute increases in thromboembolic and uterine cancer mortality (both only in women older than 55 years), so all-cause mortality was substantially reduced. In ER-negative disease, tamoxifen had little or no effect on breast cancer recurrence or mortality.

INTERPRETATION

5 years of adjuvant tamoxifen safely reduces 15-year risks of breast cancer recurrence and death. ER status was the only recorded factor importantly predictive of the proportional reductions. Hence, the absolute risk reductions produced by tamoxifen depend on the absolute breast cancer risks (after any chemotherapy) without tamoxifen.

FUNDING

Cancer Research UK, British Heart Foundation, and Medical Research Council.

Aromatase, aromatase inhibitors, and breast cancer

Estrogens are known to be important in the growth of breast cancers in both pre and postmenopausal women. As the number of breast cancer patients increases with age, the majority of breast cancer patients are postmenopausal women. Although estrogens are no longer made in the ovaries after menopause, peripheral tissues produce sufficient concentrations to stimulate tumor growth. As aromatase catalyzes the final and rate-limiting step in the biosynthesis of estrogen, inhibitors of this enzyme are effective targeted therapy for breast cancer. Three aromatase inhibitors (AIs) are now FDA approved and have been shown to be more effective than the antiestrogen tamoxifen and are well tolerated. AIs are now a standard treatment for postmenopausal patients. AIs are effective in adjuvant and first-line metastatic setting. This review describes the development of AIs and their current use in breast cancer. Recent research focuses on elucidating mechanisms of acquired resistance that may develop in some patients with long term AI treatment and also in innate resistance. Preclinical data in resistance models demonstrated that the crosstalk between ER and other signaling pathways particularly MAPK and PI3K/Akt is an important resistant mechanism. Blockade of these other signaling pathways is an attractive strategy to circumvent the resistance to AI therapy in breast cancer. Several clinical trials are ongoing to evaluate the role of these novel targeted therapies to reverse resistance to AIs. Article from the special issue on 'Targeted Inhibitors'.

Benefits and adverse effects of endocrine therapy

Endocrine-responsive tumors that are small and without nodal involvement (i.e. tumors classified as pT1 pN0) are a heterogeneous group of tumors that are associated with a low risk of relapse in the majority of the cases. Therefore, the costs and benefits of adjuvant endocrine therapy should be carefully considered within this subgroup of patients. Treatment decisions should take into consideration co-morbidities as well as the presence of other classical risk factors such as HER2 overexpression or extensive peritumoral vascular invasion. Tamoxifen or tamoxifen plus ovarian function suppression should be considered as proper endocrine therapies in premenopausal patients. Ovarian function suppression alone or ovarian ablation might also be considered adequate in selected patients (e.g. very low-risk patients, in the presence of co-morbidities or patient preference). An aromatase inhibitor should form part of standard endocrine therapy for most postmenopausal women with receptor-positive breast cancer, although patients at low risk or with co-morbid musculoskeletal or cardiovascular risk factors may be considered suitable for tamoxifen alone. Tailored endocrine treatments should be considered in patients with endocrine-responsive tumors classified as pT1 pN0. Issues focusing on safety, quality of life and subjective side effects should be routinely discussed.

The potency and clinical efficacy of aromatase inhibitors across the breast cancer continuum

The strategy of using estrogen suppression to treat breast cancer led to the development of aromatase inhibitors, including the third-generation nonsteroidal compounds anastrozole and letrozole, and the steroidal compound exemestane. Aromatase inhibitors potently inhibit aromatase activity and also suppress estrogen levels in plasma and tissue. In clinical studies in postmenopausal women with breast cancer, third-generation aromatase inhibitors were shown superior to tamoxifen for the treatment of metastatic disease. Studies of adjuvant therapy with aromatase inhibitors include (i) head-to-head studies of 5 years of the aromatase inhibitor versus 5 years of tamoxifen monotherapy; (ii) sequential therapy of 2-3 years of tamoxifen followed by an aromatase inhibitor (or the opposite sequence) versus 5 years of tamoxifen monotherapy; (iii) extended therapy with an aromatase inhibitor after 5 years of tamoxifen; and (iv) sequential therapy with an aromatase inhibitor versus aromatase inhibitor monotherapy. Recent results from the Arimidex, Tamoxifen, Alone or in Combination and Breast International Group 1-98 trials advocate using an aromatase inhibitor upfront. This article examines the clinical data with aromatase inhibitors, following a brief summary of their pharmacology.