Clinical outcomes of ethnic minority women in MA.17: a trial of letrozole after 5 years of tamoxifen in postmenopausal women with early stage breast cancer

Differential response to neoadjuvant endocrine therapy for Black/African American and White women in NCDB

PURPOSE

Compared to White women, there are higher mortality rates in Black/African American (BAA) women with hormone receptor-positive breast cancer (HR + BC) which may be partially due to differences in treatment resistance. We assessed factors associated with response to neoadjuvant endocrine therapy (NET).

METHODS

The National Cancer Database (NCDB) was queried for women with clinical stage I-III HR + BC diagnosed 2006-2017 and treated with NET. Univariate and multivariate analyses described associations between the sample, duration of NET, and subsequent treatment response, defined by changes between clinical and pathological staging.

RESULTS

The analytic sample included 9864 White and 1090 BAA women. Compared to White women, BAA women were younger, had more co-morbidities, were higher stage at presentation, and more likely to have > 24 weeks of NET. After excluding those with unknown pT/N/M, 3521 White and 365 BAA women were evaluated for NET response. On multivariate analyses, controlling for age, stage, histology, HR positivity, and duration of NET, BAA women were more likely to downstage to pT0/Tis (OR 3.0, CI 1.2-7.1) and upstage to Stage IV (OR 2.4, CI 1.002-5.6). None of the women downstaged to pT0/Tis presented with clinical stage III disease; only 2 of the women upstaged to Stage IV disease presented with clinical Stage I disease.

CONCLUSION

Independent of NET duration and clinical stage at presentation, BAA women were more likely to experience both complete tumor response and progression to metastatic disease. These results suggest significant heterogeneity in tumor biology and warrant a more nuanced therapeutic approach to HR + BC.

Systemic therapies for preventing or treating aromatase inhibitor-induced musculoskeletal symptoms in early breast cancer

BACKGROUND

Adjuvant aromatase inhibitors (AI) improve survival compared to tamoxifen in postmenopausal women with hormone receptor-positive stage I to III breast cancer. In approximately half of these women, AI are associated with aromatase inhibitor-induced musculoskeletal symptoms (AIMSS), often described as symmetrical pain and soreness in the joints, musculoskeletal pain and joint stiffness. AIMSS may have significant and prolonged impact on women's quality of life. AIMSS reduces adherence to AI therapy in up to a half of women, potentially compromising breast cancer outcomes. Differing systemic therapies have been investigated for the prevention and treatment of AIMSS, but the effectiveness of these therapies remains unclear.

OBJECTIVES

To assess the effects of systemic therapies on the prevention or management of AIMSS in women with stage I to III hormone receptor-positive breast cancer.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, WHO International Clinical Trials Registry Platform (ICTRP) and Clinicaltrials.gov registries to September 2020 and the Cochrane Breast Cancer Group (CBCG) Specialised Register to March 2021.  SELECTION CRITERIA: We included all randomised controlled trials that compared systemic therapies to a comparator arm. Systemic therapy interventions included all pharmacological therapies, dietary supplements, and complementary and alternative medicines (CAM). All comparator arms were allowed including placebo or standard of care (or both) with analgesia alone. Published and non-peer-reviewed studies were eligible.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened studies, extracted data, and assessed risk of bias and certainty of the evidence using the GRADE approach. Outcomes assessed were pain, stiffness, grip strength, safety data, discontinuation of AI, health-related quality of life (HRQoL), breast cancer-specific quality of life (BCS-QoL), incidence of AIMSS, breast cancer-specific survival (BCSS) and overall survival (OS). For continuous outcomes, we used vote-counting by reporting how many studies reported a clinically significant benefit within the confidence intervals (CI) of the mean difference (MD) between treatment arms, as determined by the minimal clinically importance difference (MCID) for that outcome scale. For dichotomous outcomes, we reported outcomes as a risk ratio (RR) with 95% CI.

MAIN RESULTS

We included 17 studies with 2034 randomised participants. Four studies assessed systemic therapies for the prevention of AIMSS and 13 studies investigated treatment of AIMSS. Due to the variation in systemic therapy studies, including pharmacological, and CAM, or unavailable data, meta-analysis was limited, and only two trials were combined for meta-analysis. The certainty of evidence for all outcomes was either low or very low certainty. Prevention studies The evidence is very uncertain about the effect of systemic therapies on pain (from baseline to the end of the intervention; 2 studies, 183 women). The two studies, investigating vitamin D and omega-3 fatty acids, showed a treatment effect with 95% CIs that did not include an MCID for pain. Systemic therapies may have little to no effect on grip strength (RR 1.08, 95% CI 0.37 to 3.17; 1 study, 137 women) or on women continuing to take their AI (RR 0.16, 95% 0.01 to 2.99; 1 study, 147 women). The evidence suggests little to no effect on HRQoL and BCS-QoL from baseline to the end of intervention (the same single study; 44 women, both quality of life outcomes showed a treatment effect with 95% CIs that did include an MCID). The evidence is very uncertain for outcomes assessing incidence of AIMSS (RR 0.82, 95% CI 0.63 to 1.06; 2 studies, 240 women) and the safety of systemic therapies (4 studies, 344 women; very low-certainty evidence). One study had a US Food and Drug Administration alert issued for the intervention (cyclo-oxygenase-2 inhibitor) during the study, but there were no serious adverse events in this or any study. There were no data on stiffness, BCSS or OS. Treatment studies The evidence is very uncertain about the effect of systemic therapies on pain from baseline to the end of intervention in the treatment of AIMSS (10 studies, 1099 women). Four studies showed an MCID in pain scores which fell within the 95% CI of the measured effect (vitamin D, bionic tiger bone, Yi Shen Jian Gu granules, calcitonin). Six studies showed a treatment effect with 95% CI that did not include an MCID (vitamin D, testosterone, omega-3 fatty acids, duloxetine, emu oil, cat's claw).  The evidence was very uncertain for the outcomes of change in stiffness (4 studies, 295 women), HRQoL (3 studies, 208 women) and BCS-QoL (2 studies, 147 women) from baseline to the end of intervention. The evidence suggests systemic therapies may have little to no effect on grip strength (1 study, 107 women). The evidence is very uncertain about the safety of systemic therapies (10 studies, 1250 women). There were no grade four/five adverse events reported in any of the studies. The study of duloxetine reported more all-grade adverse events in this treatment group than comparator group. There were no data on the incidence of AIMSS, the number of women continuing to take AI, BCCS or OS from the treatment studies.

AUTHORS' CONCLUSIONS

AIMSS are chronic and complex symptoms with a significant impact on women with early breast cancer taking AI. To date, evidence for safe and effective systemic therapies for prevention or treatment of AIMSS has been minimal. Although this review identified 17 studies with 2034 randomised participants, the review was challenging due to the heterogeneous systemic therapy interventions and study methodologies, and the unavailability of certain trial data. Meta-analysis was thus limited and findings of the review were inconclusive. Further research is recommended into systemic therapy for AIMSS, including high-quality adequately powered RCT, comprehensive descriptions of the intervention/placebo, and robust definitions of the condition and the outcomes being studied.

An Overview of the Treatment Efficacy and Side Effect Profile of Pharmacological Therapies in Asian Patients with Breast Cancer

Breast cancer (BC) among Asians accounts for ~ 40% of the global BC burden. Differences in BC risk, presentation, tumor biology, and response to treatment exist between Asian and non-Asian patients; however, Asian patients are often under-represented in clinical trials. This narrative review summarizes the efficacy and safety of pharmacological therapies for BC in Asian populations, with a focus on outcomes in Asian versus non-Asian patients treated with chemotherapy, hormone therapy, anti-human epidermal growth factor receptor-2 targeted therapies, cyclin-dependent kinase 4/6 (CDK4/6) inhibitors, mammalian target of rapamycin inhibitors, bone-targeted therapies, poly-ADP ribose polymerase, phosphoinositide 3-kinase, and checkpoint inhibitors. While most therapies have demonstrated comparable efficacy and safety in Asian and non-Asian patients with BC, differences that are largely attributed to pharmacogenetic variations between populations exist. Pharmacogenetic differences may contribute to a reduced clinical benefit of tamoxifen, whereas improved clinical outcomes have been reported with tyrosine kinase inhibitors and CDK4/6 inhibitors in Asian versus non-Asian patients with BC. In particular, Asian patients have an increased incidence of hematological toxicities, including neutropenia, although adverse events can be effectively managed using dose adjustments. Recent trials with CDK4/6 inhibitors have increased efforts to include Asians within study subsets. Future clinical trials enrolling higher numbers of Asian patients, and an increased understanding of differences in patient and tumor genetics between Asians and non-Asians, have the potential to incrementally improve the management of BC in Asian patients.

Genetics, tumor features and treatment response of breast cancer in Latinas

Breast cancer is a heterogeneous and genetic disease that has variability according to ethnicity and race with respect to incidence, clinical characteristics and prognosis. The incidence of breast cancer is lower but mortality is higher in Latinas than Caucasians in the US series. Risk factors appear to have different prevalence and impact in Latinas. Breast cancer in Latinas has particular clinic-pathological features including younger age, higher rates of triple-negative subtype and advanced stages. Molecular studies find that Latinas from every region have a specific BRCA incidence and a recurrent mutation, as well as differences in activity of molecular pathways. Treatment response rates and toxicity have also been compared, and no difference was found between Latinas and other ethnic groups.

Genomic Disparities in Breast Cancer Among Latinas

BACKGROUND

Breast cancer is the most common cancer diagnosed among Latinas in the United States and the leading cause of cancer-related death among this population. Latinas tend to be diagnosed at a later stage and have worse prognostic features than their non-Hispanic white counterparts. Genetic and genomic factors may contribute to observed breast cancer health disparities in Latinas.

METHODS

We provide a landscape of our current understanding and the existing gaps that need to be filled across the cancer prevention and control continuum.

RESULTS

We summarize available data on mutations in high and moderate penetrance genes for inherited risk of breast cancer and the associated literature on disparities in awareness of and uptake of genetic counseling and testing in Latina populations. We also discuss common genetic polymorphisms and risk of breast cancer in Latinas. In the treatment setting, we examine tumor genomics and pharmacogenomics in Latina patients with breast cancer.

CONCLUSIONS

As the US population continues to diversify, extending genetic and genomic research into this underserved and understudied population is critical. By understanding the risk of breast cancer among ethnically diverse populations, we will be better positioned to make treatment advancements for earlier stages of cancer, identify more effective and ideally less toxic treatment regimens, and increase rates of survival.

Polymorphisms in drug-metabolizing enzymes and steady-state exemestane concentration in postmenopausal patients with breast cancer

Discovery of clinical and genetic predictors of exemestane pharmacokinetics was attempted in 246 post-menopausal patients with breast cancer enrolled on a prospective clinical study. A sample was collected two hours after exemestane dosing at a 1 or 3 month study visit to measure drug concentration. The primary hypothesis was that patients carrying the low-activity CYP3A4*22 (rs35599367) SNP would have greater exemestane concentration. Additional SNPs in genes relevant to exemestane metabolism (CYP1A1/2, CYP1B1, CYP3A4, CYP4A11, AKR1C3/4, AKR7A2) were screened in secondary analyses and adjusted for clinical covariates. CYP3A4*22 was associated with a 54% increase in exemestane concentration (p<0.01). Concentration was greater in patients who reported White race, had elevated aminotransferases, renal insufficiency, lower body mass index, and had not received chemotherapy (all p<0.05), and CYP3A4*22 maintained significance after adjustment for covariates (p<0.01). These genetic and clinical predictors of exemestane concentration may be useful for treatment individualization in patients with breast cancer.

Predictive markers in elderly patients with estrogen receptor-positive breast cancer treated with aromatase inhibitors: an array-based pharmacogenetic study

So far, no reliable predictive clinicopathological markers of response to aromatase inhibitors (AIs) have been identified, and little is known regarding the role played by host genetics. To identify constitutive predictive markers, an array-based association study was performed in a cohort of 55 elderly hormone-dependent breast cancer (BC) patients treated with third-generation AIs. The array used in this study interrogates variants in 225 drug metabolism and disposition genes with documented functional significance. Six variants emerged as associated with response to AIs: three located in ABCG1, UGT2A1, SLCO3A1 with a good response, two in SLCO3A1 and one in ABCC4 with a poor response. Variants in the AI target CYP19A1 resulted associated with a favourable response only as haplotype; haplotypes with increased response association were also detected for ABCG1 and SLCO3A1. These results highlight the relevance of host genetics in the response to AIs and represent a first step toward precision medicine for elderly BC patients.

Advances in Human Biology: Combining Genetics and Molecular Biophysics to Pave the Way for Personalized Diagnostics and Medicine

Advances in several biology-oriented initiatives such as genome sequencing and structural genomics, along with the progress made through traditional biological and biochemical research, have opened up a unique opportunity to better understand the molecular effects of human diseases. Human DNA can vary significantly from person to person and determines an individual’s physical characteristics and their susceptibility to diseases. Armed with an individual’s DNA sequence, researchers and physicians can check for defects known to be associated with certain diseases by utilizing various databases. However, for unclassified DNA mutations or in order to reveal molecular mechanism behind the effects, the mutations have to be mapped onto the corresponding networks and macromolecular structures and then analyzed to reveal their effect on the wild type properties of biological processes involved. Predicting the effect of DNA mutations on individual’s health is typically referred to as personalized or companion diagnostics. Furthermore, once the molecular mechanism of the mutations is revealed, the patient should be given drugs which are the most appropriate for the individual genome, referred to as pharmacogenomics. Altogether, the shift in focus in medicine towards more genomic-oriented practices is the foundation of personalized medicine. The progress made in these rapidly developing fields is outlined.

Adverse event profile and dose modification of everolimus for advanced renal cell carcinoma in real-world Japanese clinical practice

OBJECTIVE

The aim of the study was to assess the safety and efficacy of everolimus therapy for advanced renal cell carcinoma in Japanese patients receiving real-world care.

METHODS

Patients who had been treated with everolimus for advanced renal cell carcinoma at 39 Japanese medical centers between January 2010 and November 2011 were retrospectively investigated to assess adverse events and the time to treatment failure.

RESULTS

A total of 180 patients were identified. Their median age was 65 years (range 23-93). The median time to treatment failure was 2.9 months (95% confidence interval 2.4-3.4). The median time to treatment failure was significantly longer in patients with dose modification (4.2 months; 95% confidence interval 3.4-5.0) than in patients without dose modification (1.7 months; 95% confidence interval 1.0-2.3; P < 0.01) after experiencing adverse events. Stomatitis (44%) was the most frequent adverse event, followed by thrombocytopenia (31%), anemia (22%), interstitial pneumonia (22%) and hyperglycemia (17%). Interstitial pneumonia was the most frequent cause of discontinuation in patients who discontinued everolimus due to intolerability regardless of the dose modification status. None of the patients with dose modification of everolimus discontinued everolimus due to thrombocytopenia or leukopenia.

CONCLUSIONS

The adverse event profile of everolimus may differ between Japanese and Caucasian patients. Dose modification of everolimus might be associated with longer treatment duration in patients with advanced renal cell carcinoma. Further studies are required to clarify this association. Interstitial pneumonia may be difficult to overcome by dose modification.

Time course of arthralgia among women initiating aromatase inhibitor therapy and a postmenopausal comparison group in a prospective cohort

BACKGROUND

More than 80,000 postmenopausal breast cancer patients in the United States each year are estimated to begin a 5-year course of aromatase inhibitors (AIs) to prevent recurrence. AI-related arthralgia (joint pain and/or stiffness) may contribute to nonadherence, but longitudinal data are needed on arthralgia risk factors, trajectories, and background in postmenopause. This study sought to describe 1-year arthralgia trajectories and baseline covariates among patients with AI and a postmenopausal comparison group.

METHODS

Patients initiating AIs (n = 91) were surveyed at the time of AI initiation and at 6 repeated assessments over 1 year. A comparison group of postmenopausal women without breast cancer (n = 177) completed concomitantly timed surveys. Numeric rating scales (0-10) were used to measure pain in 8 joint pair groups (bilateral fingers, wrists, elbows, shoulders, hips, knees, ankles, and toes). Poisson regression models were used to analyze arthralgia trajectories and risk factors.

RESULTS

By week 6, the AI-initiating group had more severe arthralgia than did the comparison group (ratio of means = 1.8, 95% confidence interval = 1.24-2.7, P = .002), adjusting for baseline characteristics. Arthralgia then worsened further over 1 year in the AI group. Menopausal symptom severity and existing joint-related comorbidity at baseline among women initiating AI were associated with more severe arthralgia over time.

CONCLUSIONS

Patients initiating AI should be told about the timing of arthralgia over the first year of therapy, and advised that it does not appear to resolve over the course of a year. Menopausal symptoms and joint-related comorbidity at AI initiation can help identify patients at risk for developing AI-related arthralgia.

Pharmacogenetics of aromatase inhibitors

Aromatase inhibitors (AIs) are an important class of endocrine drugs used in the treatment of early and advanced breast cancer in postmenopausal women. A number of studies have taken candidate approaches to assess the role of variants in genes encoding enzymes important in AI metabolism, notably CYP19A1 (aromatase), in AI response. These studies have shown conflicting, but interesting, results suggesting that CYP19A1 variants may be important in both the efficacy and toxicity of AIs. A recent genome-wide association study has identified a variant, creating an estrogen response element in TCL1A, which is associated with an increased risk of the musculoskeletal side effects associated with AI use. As breast cancer incidence increases, predictive biomarkers of response to AIs will become more important to ensure the most effective use of endocrine treatments.

Physical distress and cancer care experiences among Chinese-American and non-Hispanic White breast cancer survivors

OBJECTIVE

The number of Chinese-American breast cancer survivors (BCS) is increasing as a result of increasing incidence rates. There has been little research on Chinese BCS' follow-up cancer care. This qualitative study aims to understand how Chinese-American BCS experience and cope with physical distress relative to non-Hispanic White (NHW) survivors.

METHODS

Seventy-one BCS (37 Chinese immigrant, 7 US-born Chinese, 27 NHW) were recruited from the Greater Bay Area Cancer Registry to participate in focus group discussions or one-on-one interviews about their survivorship experiences. All BCS were diagnosed with breast cancer at stage 0-IIA between 2006 and 2009, and had survived for 1-4 years without recurrence. Interviews were conducted in Cantonese, Mandarin, or English. Data analyses followed established qualitative methods of content analysis.

RESULTS

BCS experienced pain and side effects from radiation, surgery, and hormonal therapy. Physical distress subsequently caused emotional concerns about recurrence or metastasis. Most BCS consulted physicians about their physical distress. Chinese immigrant BCS were less likely to have their issues resolved compared to NHW and US-born Chinese who were more likely to question physicians, ask for referrals, and make repeat attempts if their problems were not resolved. Some Chinese immigrant BCS turned to Traditional Chinese Medicine for relief or accepted the idea that physical distress was part of survivorship.

CONCLUSION

Chinese immigrant BCS may be at risk for greater distress compared with US-born Chinese and NHW BCS because of cultural norms that make them less inclined to express their needs to physicians or challenge physicians when their needs are not met. Furthermore, they may express symptoms in culturally unique ways (e.g., hot-cold imbalances). Further research is needed to determine how to best improve survivorship care experiences in this understudied population, with the goal of decreasing BCS' physical distress and improving quality of life.

Health-related quality of life, psychological distress, and adverse events in postmenopausal women with breast cancer who receive tamoxifen, exemestane, or anastrozole as adjuvant endocrine therapy: National Surgical Adjuvant Study of Breast Cancer 04 (N-SAS BC 04)

Health-related quality of life (HRQOL), symptoms of depression, and adverse events (AEs) were compared between Japanese postmenopausal patients with hormone-sensitive breast cancer (BC) who received adjuvant tamoxifen, exemestane, or anastrozole in an open-labeled, randomized, multicenter trial designated as the National Surgical Adjuvant Study of Breast Cancer (N-SAS BC) 04 substudy of the Tamoxifen Exemestane Adjuvant Multinational (TEAM) trial. During the first year of treatment, HRQOL and symptoms of depression were analyzed using the Functional Assessment of Cancer Therapy-Breast (FACT-B) and its Endocrine Symptom Subscale (ES), and the Center for Epidemiologic Studies Depression Scale (CES-D), respectively. In addition, predefined AEs were analyzed. A total of 166 eligible patients were randomly assigned to receive adjuvant tamoxifen, exemestane, or anastrozole. FACT-B scores increased after treatment began and remained significantly higher in the tamoxifen group than in the exemestane group or anastrozole group during the first year (P = 0.045). FACT-B scores were similar in the exemestane group and anastrozole group. ES scores and CES-D scores were similar in all treatment groups. Arthralgia and fatigue were less frequent, but vaginal discharge was more frequent in the tamoxifen group than in the exemestane group or anastrozole group. HRQOL was better in Japanese postmenopausal women treated with tamoxifen than those treated with exemestane or anastrozole. HRQOL and AEs were similar with exemestane and anastrozole. Given the results of the TEAM trial, upfront use of tamoxifen followed by an aromatase inhibitor (AI) may be an important option for adjuvant endocrine therapy in Japanese postmenopausal women.

An update on ethnic differences in drug metabolism and toxicity from anti-cancer drugs

INTRODUCTION

Based on recent emerging evidence of inter-ethnic differences in drug response and toxicity, ethnic diversity in pharmacokinetics, pharmacogenomics and clinical outcomes are being increasingly investigated. Ultimately, this will promote improved understanding of inter-individual differences in the pharmacokinetics and tolerance of cytotoxic drugs.

AREAS COVERED

This article reviews potential explanations for the observed ethnic differences in treatment outcomes and provides clinical data to support this concept. A literature search was implemented on PubMed and PharmGKB to investigate the areas of ethnic differences in pharmacogenomics, pharmacogenetics and clinical outcomes of cancer therapies.

EXPERT OPINION

There has been a relative paucity of clinical evidence linking genetic polymorphisms of genes encoding drug-metabolizing enzymes to the pharmacokinetics, pharmacodynamics and tolerance of anti-cancer drugs. Future research should focus on studies using large sample sizes, in the hope that they will provide results of high clinical significance. Due to the potential for ethnic differences to impact on both toxicities and benefits of systemic cancer therapies, the development of new therapeutic agents should include patients from diverse geographical ancestries in each phase of drug development.

Single nucleotide polymorphisms of CYP19A1 predict clinical outcomes and adverse events associated with letrozole in patients with metastatic breast cancer

PURPOSE

The CYP19A1 gene encodes the aromatase enzyme involved in the peripheral conversion of androgen to estrogen. We evaluated the efficacy of the aromatase inhibitor letrozole in patients with metastatic breast cancer (MBC) as related to DNA polymorphisms of CYP19A1.

PATIENTS AND METHODS

One hundred and nine patients with hormone receptor-positive MBC were treated with letrozole alone or in combination with a GnRH agonist. DNA was isolated from peripheral blood and genotyped for 46 single nucleotide polymorphisms (SNPs) of CYP19A1.

RESULTS

Among 46 SNPs examined, rs700518, rs10459592, and rs4775936 were significantly associated with higher clinical benefit rate (CBR, CR + PR + SD ≥ 6 months) (OR = 2.61 [95% CI; 1.13-6.03], P = 0.025; OR = 2.45 [95% CI; 1.06-5.65], P = 0.036; OR = 2.60 [95% CI; 1.12-6.02], P = 0.026, respectively). Median time to progression (TTP) was improved without statistical significance in patients having an over-dominant form of rs700518. In haplotype analysis, the specific haplotypes M_1_3 and M_2_1 showed a strong association with CBR (OR = 3.37 [95% CI 1.43-7.90], P = 0.005; OR = 5.33 [95% CI 1.63-17.45], P = 0.006, respectively). There was a statistically significant difference in TTP in patients with haplotype M_1_3 (5.61 months [95% CI 0.00-11.45] vs. 11.08 months [95% CI 6.75-15.42], P = 0.040) and M_2_1 (7.31 months [95% CI 4.63-9.99] vs. 12.95 months [95% CI 9.27-16.63], P = 0.038). Haplotypes M_3_5 (OR = 11.25 [95% CI 1.17-108.28], P = 0.01) and M_5_3 (OR = 4.12, [95% CI 1.09-15.61], P = 0.03) were associated with side effects of arthralgia and hot flash, respectively.

CONCLUSION

The genetic variations of CYP19A1 were significantly associated with clinical efficacy, suggesting potential predictive markers for letrozole treatment in patients with metastatic breast cancer.

Health-related quality of life and psychological distress of breast cancer patients after surgery during a phase III randomized trial comparing continuation of tamoxifen with switching to anastrozole after adjuvant tamoxifen for 1-4 years: N-SAS BC 03

To investigate whether the health-related quality of life (HRQOL) of patients switching from tamoxifen to anastrozole in a randomized trial is identical to that of those who continued tamoxifen after 1-4 years of adjuvant tamoxifen in Japanese postmenopausal breast cancer patients. Eligible patients for the randomized trial, the National Surgical Adjuvant Study of Breast Cancer 03, were recurrence-free postmenopausal women who had received definitive surgery for primary breast cancer with positive hormone receptor(s), and had been taking tamoxifen for 1-4 years postoperatively. They were randomly assigned to continue tamoxifen or to switch to anastrozole for a total duration of five years. Subjects were asked to reply to a self-administered QOL questionnaire survey to assess HRQOL (FACT-B [breast cancer scale], FACT-ES [endocrine symptom scale]) and psychological distress (CES-D: Center for Epidemiologic Studies Depression scale) at randomization (baseline), 3 months, 1, and 2 years after randomization, respectively. At baseline 694 patients (346 in the tamoxifen group and 348 in the anastrozole group) responded to the survey. The total scores of FACT-G, FACT-ES, and those of the FACT-G physical well-being subscale were statistically significantly better in the tamoxifen group than in the anastrozole group (P = 0.042, 0.038, and 0.005, respectively). However, there was no statistically significant difference between the treatment groups in the CES-D scores. Continuation of tamoxifen treatment after adjuvant tamoxifen for 1-4 years may provide Japanese breast cancer patients with better HRQOL than by switching to anastrozole.

Phase III randomized adjuvant study of tamoxifen alone versus sequential tamoxifen and anastrozole in Japanese postmenopausal women with hormone-responsive breast cancer: N-SAS BC03 study

Clinical trials conducted in Western countries have shown that aromatase inhibitors are associated with better disease-free survival (DFS) than tamoxifen in postmenopausal early breast cancer. Because pharmacogenetic differences in drug-metabolizing genes may cause ethnic differences, assessment of the efficacy and tolerability of aromatase inhibitors in non-white women is warranted. This open-label, randomized clinical trial included 706 postmenopausal Japanese women with hormone-receptor-positive breast cancer, who had received tamoxifen for 1 to 4 years as adjuvant therapy. This study was closed early after entry of approximately 28% of the initially planned patients. They were randomly assigned to either switch to anastrozole or to continue tamoxifen for total treatment duration of 5 years. Primary endpoints were DFS and adverse events. At a median follow-up of 42 months, the unadjusted hazard ratio was 0.69 (95% confidence interval, 0.42-1.14; P = 0.14) for DFS and 0.54 (95% CI, 0.29-1.02; P = 0.06) for relapse-free survival (RFS), both in favor of anastrozole. The incidence of thromboembolic events in the tamoxifen group and bone fractures in the anastrozole group was not excessively high. Switching from tamoxifen to anastrozole was likely to decrease disease recurrence in postmenopausal Japanese breast cancer patients. Ethnic differences in major adverse events may be attributable to a low baseline risk of these events in Japanese.

Breast cancer in Latinas: gene expression, differential response to treatments, and differential toxicities in Latinas compared with other population groups

Disparities in clinical outcomes of breast cancer have been described among different racial and ethnic groups in the U.S. Convincing data exist showing that Latina women have a lower incidence of breast cancer but a higher breast cancer-related mortality rate compared with white women. Noticeable differences in breast cancer incidence are present even within different Latina subsets with a higher incidence in second- and third-generation women compared with foreign born. An increasing amount of data exists pointing to significant differences in the genetics and biology of breast cancer in Latinas as a significant contributor to the higher mortality, including a higher incidence of triple-negative breast cancers (which do not overexpress HER-2 protein and are negative for estrogen receptors and progesterone receptors). Other social and environmental factors are likely to play a significant role as well, including a lower rate of screening mammography, variable access to medical care, among others. Recent data are inconclusive regarding differences among racial/ethnic groups in the response to chemotherapy. Data on racial/ethnic variations in the pharmacogenomics of chemotherapy, endocrine treatments, and toxicity are more limited, with some data suggesting differences in frequencies of polymorphisms of genes involved in the metabolism of some of these agents. Further studies are needed on this subject.

Letrozole: a review of its use in the treatment of postmenopausal women with hormone-responsive early breast cancer

Letrozole (Femara) is a third-generation, nonsteroidal aromatase inhibitor. Adjuvant therapy with letrozole is more effective than tamoxifen in postmenopausal women with hormone-responsive early breast cancer, and extended adjuvant therapy with letrozole after the completion of adjuvant tamoxifen therapy is more effective than placebo in this patient population; letrozole is generally well tolerated. Ongoing trials will help answer outstanding questions regarding the optimal duration of letrozole therapy in early breast cancer and its efficacy compared with other third-generation aromatase inhibitors such as anastrozole. In the meantime, letrozole should be considered a valuable option in the treatment of postmenopausal women with hormone-responsive early breast cancer, both as adjuvant and extended adjuvant therapy.

Reporting of race and ethnicity in breast cancer research: room for improvement

Health disparities in breast cancer outcomes according to race/ethnicity are well documented. Randomized clinical trials (RCT) offer an opportunity to evaluate differences in disease biology and response to therapy that may contribute to disparities. We conducted a PubMed search to identify all English language original reports of breast cancer RCT from October 2001 to October 2006. The primary outcomes of interest were reporting of accrual and results by race or ethnicity of trial subjects. We evaluated the correlation between study characteristics and reporting of race/ethnicity. A total of 197 eligible trials were identified among 29 journals. Accrual was reported by race in 17% of studies and results analyzed by race in only 2%. Reporting of race was associated with National Cancer Institute funding (38 vs. 13%, P = 0.001), US cooperative group trials (52 vs. 13%, P < 0.0001), trials with US sites (43 vs. 5%, P < 0.0001), and trials enrolling > 500 subjects (24 vs. 12%, P = 0.055). Pharmaceutical industry funding, # of centers, stage of disease, nature of experimental intervention and study outcomes were not associated with reporting of race. Among US studies reporting trial accrual by race/ethnicity, the mean accrual distribution was 81% white, 7.6% black, 9.6% Asian, and 7.2% Hispanic subjects. The majority of breast cancer RCT fail to report the race/ethnicity of participants. Low accrual of black subjects and failure to report accrual and outcomes by race in RCT may contribute to difficulty in understanding and overcoming health disparities in breast cancer.

Improving compliance and persistence to adjuvant tamoxifen and aromatase inhibitor therapy

Better compliance and persistence with therapy are associated with improved patient outcomes. As more and more patients survive breast cancer, compliance with adjuvant therapy becomes increasingly important. In clinical trials, compliance with adjuvant endocrine therapy among women with breast cancer is usually high. Retrospective analyses of databases and medical records from clinical practice, insurance databases of prescription refills, and survey data show a significant decrease in persistence after 12 months of therapy. With ongoing therapy, a further decline in persistence of up to 50% has been reported. A consistent methodology is needed to measure patient behavior and identify patients who are not adhering to therapy. Promising strategies for enhancing adherence to treatment in clinical practice include improving access to health care, increasing patient satisfaction, managing side effects, patient education, and better communication between the patient and health care provider. Positive relationships between patients and their health care providers, and frequent monitoring and feedback, may be most effective. While the lack of conformity across studies in measuring makes cross-study comparisons difficult, this review evaluates the available data regarding compliance and persistence with adjuvant endocrine therapies for breast cancer (tamoxifen and aromatase inhibitors) and presents strategies for improving adherence.

Safety of adjuvant endocrine therapy in postmenopausal women with breast cancer

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

ERbeta in breast cancer--onlooker, passive player, or active protector?

The role of estrogen exposure in breast cancer risk is well-documented, and both estrogen synthesis and actions through the estrogen receptor (ER) have been targeted by therapies to control hormone-dependent breast cancer. The discovery of a second ER form and its therapeutic implications sparked great interest. Both the original ERalpha and the more recently identified ERbeta subtypes bind and respond similarly to many physiological and pharmacological ligands. However, differences in phytoestrogen binding have been noted, and subtype-specific ligands have been developed. Cell-based assays show that ERbeta and its variants are generally less active on gene transcription than ERalpha, and may influence ERalpha activity; however, both gene- and cell-specific responses occur, and nongenomic activities are less well explored. Specific ligands, and methods to disrupt or eliminate receptor subtype expression in animal and cell models, demonstrate that the ERs have both overlapping and distinct biological functions. Overall, in cell-based studies, ERalpha appears to play a predominant role in cell proliferation, and ERbeta is suggested to be antiproliferative. The potential for distinct populations of breast tumors to be identified based on ER subtype expression, and to exhibit distinct clinical behaviors, is of greatest interest. Several studies suggest that the majority of ER-positive tumors contain both subtypes, but that some tumors contain only ERbeta and may have distinct clinical behaviors and responses. Expression of ERbeta together with ERalpha favors positive responses to endocrine therapy in most studies, and additional studies to determine if the addition of ERbeta to ERalpha as a tumor marker is of clinical benefit are warranted. In contrast, the positive association between ERbeta and HER2 expression in high-grade ERalpha-negative breast cancer does not favor positive responses to endocrine therapy. Expression of ERbeta in specific clinical subpopulations, and the potential for therapies targeting ERbeta specifically, is discussed.

Intent-to-treat analysis of the placebo-controlled trial of letrozole for extended adjuvant therapy in early breast cancer: NCIC CTG MA.17

BACKGROUND

MA.17 evaluated letrozole or placebo after 5 years of tamoxifen and showed significant improvement in disease-free survival (DFS) for letrozole [hazard ratio (HR) 0.57, P = 0.00008]. The trial was unblinded and placebo patients were offered letrozole.

PATIENTS AND METHODS

An intent-to-treat analysis of all outcomes, before and after unblinding, on the basis of the original randomization was carried out.

RESULTS

In all, 5187 patients were randomly allocated to the study at baseline and, at unblinding, 1579 (66%) of 2383 placebo patients accepted letrozole. At median follow-up of 64 months (range 16-95), 399 recurrences or contralateral breast cancers (CLBCs) (164 letrozole and 235 placebo) occurred. Four-year DFS was 94.3% (letrozole) and 91.4% (placebo) [HR 0.68, 95% confidence interval (CI) 0.55-0.83, P = 0.0001] and showed superiority for letrozole in both node-positive and -negative patients. Corresponding 4-year distant DFS was 96.3% and 94.9% (HR 0.80, 95% CI 0.62-1.03, P = 0.082). Four-year overall survival was 95.1% for both groups. The annual rate of CLBC was 0.28% for letrozole and 0.46% for placebo patients (HR 0.61, 95% CI 0.39-0.97, P = 0.033).

CONCLUSIONS

Patients originally randomly assigned to receive letrozole within 3 months of stopping tamoxifen did better than placebo patients in DFS and CLBC, despite 66% of placebo patients taking letrozole after unblinding.