Summary of aromatase inhibitor clinical trials in postmenopausal women with early breast cancer

Initiation of Oral Endocrine Therapy and Survival Benefit Among Women with Early-Stage Breast Cancer

Introduction: Endocrine therapy (ET) is the cornerstone of systemic treatment for patients with estrogen receptor positive breast cancer, but its uptake and adherence need further improvement. This observational study assessed ET initiation and 1-year adherence and its survival benefit among female Medicare beneficiaries with early-stage breast cancer. Materials and Methods: This retrospective cohort study analyzed the linked 2011-2019 Surveillance, Epidemiology, and End Results-Medicare data. Female beneficiaries newly diagnosed with hormone receptor positive, stage I-III breast cancer were included. Beneficiaries who initiated tamoxifen, anastrozole, letrozole, or exemestane within 3 months after cancer diagnosis were defined as initiators (n = 24,289), and those who never initiated these treatments were noninitiators (n = 8,899). Adherence was measured using proportion of days covered (PDC) in the continuous 12 months follow-up period. Multivariable logistic regression models were used to assess factors associated with ET initiation and adherence (PDC ≥ 80%), controlling for covariates. Weighted Cox proportional hazard models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) of all-cause and breast cancer related mortality between initiators and noninitiators and by adherence status. Results: Among eligible female beneficiaries (n = 55,893), 43% initiated ET within 3 months of cancer diagnosis. Among initiators, 77% had PDC ≥ 80% during the first year. Patient's demographics (e.g., older age, race/ethnicity) and baseline health services utilization (e.g., mammography) were associated with ET initiation and adherence. ET initiation and adherence was associated with reduced risk of all-cause (adjusted HR = 0.62, 0.59-0.66; HR = 0.55, 0.53-0.59; respectively) and breast cancer related (adjusted HR = 0.57, 0.50-0.64; HR = 0.41, 0.36-0.47; respectively) mortality compared with noninitiators. Conclusion: Women with early-stage breast cancer who initiate ET and are adherent to treatment may achieve survival benefits compared with noninitiators.

Factors influencing five-year adherence to adjuvant endocrine therapy in breast cancer patients: A systematic review

Purpose

This systematic review aimed to determine the rate and identify correlates of adherence and persistence over five years of treatment with adjuvant endocrine therapy in female breast cancer patients.

Methods

Relevant articles were identified from Medline, Embase, AMED, PsycINFO, International Pharmaceutical Abstracts, and APA PsycArticles. Studies that measured patient adherence in the implementation or persistence phase for a period of at least five years using objective or multiple measures of adherence and investigated correlates of adherence were included. The titles, abstracts and full articles were screened and reviewed by two authors and any discrepancies were discussed with a third author.

Results

Twenty-six studies were included. Mean rate of adherence at five-year for implementation phase was 66.2% (SD = 17.3%), and mean persistence was 66.8% (SD = 14.5%). On average, adherence decreased by 25.5% (SD = 9.3%) from the first to fifth year. Higher rate of adherence was observed through self-report in comparison to database or medical record. Older age, younger age, higher comorbidity index, depression and adverse effects were associated with lower adherence. Treatment with aromatase inhibitors, received chemotherapy, and prior medication use were associated with improved adherence.

Conclusion

Adherence to adjuvant endocrine therapy decreased from the first to fifth year of treatment. On average, one-third of patients were not adherent to treatment by the fifth year. Nineteen recurring factors were found to be significantly associated with long-term adherence in multiple studies. Further research using objective or multiple measures of adherence are needed to improve validity of results.

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On average, adherence fell by 25.5% from the first to the fifth year of treatment.

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Self-reported adherence may overestimate patient adherence.

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Nineteen recurring factors were associated with adherence.

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Having adverse effects was negatively associated with adherence.

Exemestane may be less detrimental than letrozole to bone health in women homozygous for the UGT2B17*2 gene deletion

PURPOSE

UGT2B17 gene deletion (UGT2B17*2) has been reported to affect bone health as well as the pharmacokinetics of aromatase inhibitor (AI) drugs such as exemestane. The goal of this study was to assess associations between UGT2B17 gene deletion and bone health prior to and after 24 months of AI treatment in postmenopausal women with hormone receptor positive (HR+) breast cancer.

METHODS

Bone health in women with HR+ breast cancer enrolled on the prospective randomized Exemestane and Letrozole Pharmacogenetics (ELPh) trial was determined by measuring bone turnover markers (BTM) and bone mineral density (BMD) pre-treatment and after 3 BTM and 24 BMD months of treatment with either the steroidal AI exemestane or the nonsteroidal AI letrozole. DNA samples were genotyped for UGT2B17*2.

RESULTS

Of the 455 subjects included in the analyses, 244 (53.6%) carried at least one copy of UGT2B17*2. UGT2B17*2 was associated with lower pre-treatment BMD at the hip (P = 0.01) and spine (P = 0.0076). Letrozole treatment was associated with a greater decrease in BMD of the hip (P = 0.03) and spine (P = 0.03) than exemestane. UGT2B17 genotype was not associated with changes in BMD from 24 months of AI treatment, though in UGT2B17*2 homozygous patients, there was a trend toward greater decreases in BMD of the spine from treatment with letrozole compared with exemestane (P = 0.05).

CONCLUSION

UGT2B17*2 may be associated with lower baseline BMD in women with HR+ breast cancer. Exemestane is less detrimental to bone health than letrozole in postmenopausal women treated with AI, and this effect may be confined to patients carrying UGT2B17*2, though this finding requires independent validation.

Impact of the OATP1B1 c.521T>C single nucleotide polymorphism on the pharmacokinetics of exemestane in healthy post-menopausal female volunteers

WHAT IS KNOWN AND OBJECTIVE

OATP1B1 mediates the transport of a diverse range of amphiphilic organic compounds that include bile acids, steroid conjugates and hormones. This retrospective pharmacogenetic study was conducted to assess the impact of the OATP1B1 c.521T>C single nucleotide polymorphism (SNP) on the pharmacokinetics of the steroidal aromatase inhibitor drug exemestane in healthy volunteers.

METHODS

Exemestane (25 mg) was administered orally to 14 healthy post-menopausal women. All of the 14 subjects were sampled for pharmacokinetic (PK) analyses and retrospectively genotyped for OATP1B1 c.521T>C (rs 4149056).

RESULTS AND DISCUSSION

Of the 14 subjects enrolled in the study, five were carriers of the minor C allele (OATP1B1 c.521TC+CC) and the remaining nine were carriers of the OATP1B1 c.521TT genotype. PK was assessed over 8 hours post-dosing. Our results showed statistically significant differences (P=.04) in the plasma exemestane AUC_0-8 between the OATP1B1 genotype groups. Our data also showed statistically significant differences (P=.04) in the plasma AUC_0-8 of 17-hydroexemestane (the major biologically active metabolite) between the OATP1B1 genotype groups.

WHAT IS NEW AND CONCLUSION

Our data suggest that the OAPTP1B1 c.521T>C SNP may influence exemestane pharmacokinetics in humans.

COX2 induction: a mechanism of endocrine breast cancer resistance?

PURPOSE

Urine prostaglandin E2 (PGE2) levels have shown to be a risk factor of breast cancer, and the use of nonsteroidal anti-inflammatory drugs (NSAIDs) is known to be beneficial in preventing breast cancer risk and/or recurrence with or without aromatase inhibitors. We hypothesized that the use of an aromatase inhibitor triggers the activation of the inflammatory pathway via release of PGE2.

METHODS

A single oral 25 mg dose of an aromatase inhibitor (exemestane) was given to 14 healthy postmenopausal female volunteers. Blood and urine samples were collected between 0 and 72 h post-dosing for pharmacokinetic and pharmacodynamic analysis.

RESULTS

Our findings showed that urine PGE2 levels were markedly increased 72 h after exemestane administration (average pre-dosing PGE2 levels, 4061.1 pg/mL vs. post-dosing average PGE2 levels, 10732.5 pg/mL, P = 0.001, Wilcoxon Rank Test). Out of 14 subjects enrolled in the study, one subject showed no change in PGE2; another showed a 23-fold decreased in PGE2; and the remaining 12 showed an average of 8.4-fold increase in PGE2 levels (range 1.3-30.5, standard deviation 9.2) after exemestane administration. We found no statistically significant correlations between fold increase in urine PGE2 levels and the pharmacokinetics of either exemestane or 17-hydroexemestane (major in vivo metabolite of exemestane).

CONCLUSION

Our results indicate that one of the pharmacological effects to aromatase inhibitors (e.g., exemestane) involves the activation of the inflammatory pathway via release of PGE2. Further in vitro mechanistic and in vivo translational studies designed to elucidate the role of this newly discovered effect are now warranted.

Age-related differences in persistence in women with breast cancer treated with tamoxifen or aromatase inhibitors in Germany

AIMS

To study age-related persistence in postmenopausal women with endocrine-responsive breast cancer treated with tamoxifen (TAM) and aromatase inhibitors (AI).

METHODS

Data on 29,245 patients diagnosed with metastatic or non-metastatic breast cancer (BC) and initially treated with TAM or AI between 2004 and 2013 were included. The primary outcome measure was the age-dependent rate of discontinuation of endocrine treatment within 5years after initiation. Discontinuation of therapy was defined as a period of at least 90days without treatment. A multivariate Cox regression model was created to determine the influence of age on the risk of discontinuation. Health insurance type (private/statutory), type of care (gynecological/general), region (West/East Germany), concomitant diagnoses (depression, osteoporosis, and diabetes), and Charlson Comorbidity Score were included as covariates.

RESULTS

The mean ages of the women in the <70 and ≥70 groups were 55.9 (SD: 9.7) and 77.4 (SD: 5.4) years, respectively. Within 5years after treatment initiation, 88.8% of women <70 of age and 82% of women ≥70 years of age had terminated treatment (p-value<0.001). Patients aged ≥70 exhibited a lower risk of treatment discontinuation than patients aged <70 (HR=0.75, 95% CI: 0.66-0.85). Furthermore, gynecological practices, disease management programs, and high Charlson scores increased persistence.

CONCLUSIONS

Overall, the present study indicates that persistence rates are low in both women with BC aged <70 and those aged ≥70 years. We also found that younger women with BC are at a higher risk of treatment discontinuation than older women.

Impact of UGT2B17 Gene Deletion on the Pharmacokinetics of 17-Hydroexemestane in Healthy Volunteers

Exemestane is an aromatase inhibitor drug used for the treatment of hormone-dependent breast cancer. 17-Hydroexemestane, the major and biologically active metabolite of exemestane in humans, is eliminated via glucuronidation by the polymorphic UGT2B17 phase II drug-metabolizing enzyme. Previous microsomal studies have shown that UGT2B17 gene deletion affects the intrinsic hepatic clearances of 17-hydroexemestane in vitro. In this open-label study we set out to assess the effect of UGT2B17 gene deletion on the pharmacokinetics of 17-hydroexemestane in healthy female volunteers with and without UGT2B17. To achieve this goal, 14 healthy postmenopausal women (8 carriers of the homozygous UGT2B17 wild-type allele and 6 carriers of the homozygous UGT2B17 gene-deletion allele) were enrolled and invited to receive a single 25-mg oral dose of exemestane. Pharmacokinetics was assessed over 72 hours postdosing. Our results showed that there were statistically significant differences in plasma 17-hydroexemestane AUC0-∞ (P = .0007) and urine 17-hydroexemestane C24h (P = .001) between UGT2B17 genotype groups. Our data suggest that UGT2B17 gene deletion influences 17-hydroexemestane pharmacokinetics in humans.

Current approaches for neoadjuvant chemotherapy in breast cancer

Compared to adjuvant chemotherapy, the administration of the same regimen in the neoadjuvant setting provides women with identical improvements in disease free and overall survival. Neoadjuvant chemotherapy may offer benefits to properly selected women such as broadening surgical options and enhancing the likelihood of breast conservation. Assessment of response to neoadjuvant chemotherapy provides women with an individualized estimate of prognosis. For example, a woman who achieves a complete pathological response following neoadjuvant chemotherapy has a very low risk of recurrence compared to a woman with similar tumor characteristics and a large residual disease. In this review we will provide a historical perspective and discuss the aims of neoadjuvant chemotherapy in primary operable breast cancer; as well as appropriate patient selection, treatment strategies, response monitoring, and postoperative care. We will also discuss the attractiveness of this approach to study the mechanism of action of standard and novel agents, and the role of predictive biomarkers of response to treatment and outcomes.

The Patient's Anastrozole Compliance to Therapy (PACT) Program: a randomized, in-practice study on the impact of a standardized information program on persistence and compliance to adjuvant endocrine therapy in postmenopausal women with early breast cancer

BACKGROUND

Compliance and persistence are often overlooked in adjuvant breast cancer treatment.

PATIENTS AND METHODS

PACT was a prospective, multicenter, randomized, open, parallel-group study assessing whether educational materials (EMs) enhanced compliance with aromatase inhibitor (AI) therapy in postmenopausal women with early, hormone-receptor-positive (HR+) breast cancer. The primary end points were compliance (proportion taking ≥ 80% anastrozole) at 12 months and persistence (proportion reporting anastrozole intake during the study period).

RESULTS

Four thousand eight hundred and forty-four patients were randomly assigned 1:1 to receive standard therapy or standard therapy with EMs. There was no difference between arms in compliance (N = 2740; 88.5%/88.8%, respectively, P = 0.81) or persistence rates (N = 2740; 40.5%/43.0%, respectively, P = 0.18). Modified end point analyses found no differences in compliance between arms based on the classification of: (i) patients with missing documentation or follow-up visit <9 months as non-compliant (N = 4397, P = 0.15); (ii) patients with early (≤ 292 days) 12-month follow-up documentation excluded (N = 4091, P = 0.19); (iii) patients reaching ≥ 80% compliance during individual follow-up as compliant (N = 4397, P = 0.26). Modified persistence analyses found no difference between arms (N = 4397, P = 0.37).

CONCLUSIONS

Addition of EMs to standard therapy did not significantly affect compliance and persistence with adjuvant anastrozole. CLINICALTRIALS ID: NCT00555867.

Persistence in patients with breast cancer treated with tamoxifen or aromatase inhibitors: a retrospective database analysis

Compliance and persistence are often underestimated in breast cancer (BC) treatment. The aim of our study was to analyze the persistence with tamoxifen (TAM) and aromatase inhibitors (AI) in postmenopausal women with hormone-receptor-positive BC and to identify determinants of non-persistence. We used data of the Disease Analyzer database (IMS HEALTH, Germany) including 2,067 general practices and 397 gynecological practices. Out of a dataset of 15 million patients, we identified BC patients with a first-time TAM or AI prescriptions from October 2001 to December 2010. For persistence analyses, 12,412 women on tamoxifen, 2,796 on anastrozole, 647 on exemestane, and 1,657 on letrozole met the inclusion/exclusion criteria. Within 3 years of follow-up, the discontinuation rates increased to 52.2 % for tamoxifen, 47 % for anastrozole, 55.1 % for exemestane, and 44.3 % for letrozole treated women. A minor proportion of patients switched to a different endocrine treatment; 33 % tamoxifen, 20 % anastrozole, 22.9 % exemestane, and 23 % letrozole. The multivariate hazard ratios of the cox regression models showed that patients younger than 50 were most likely to discontinue initial therapy when compared with the reference group of women over 70 (p < 0.001). In contrast, patients treated in gynecologist practice had significantly longer persistence than patients who obtained their prescriptions in general practitioner practice (p < 0.001). In addition, the presence of the co morbidities like diabetes (p < 0.001) or depression (p < 0.002) was also associated with decreased risk of treatment discontinuation. Persistence with all endocrine treatments in women with hormone-receptor-positive BC is low and needs to be significantly increased to improved outcome in clinical practice. Further research is required to understand this complex issue.

Impact of oncology-related direct-to-consumer advertising: association with appropriate and inappropriate prescriptions

BACKGROUND

Little is known about the impact of direct-to-consumer advertising (DTCA) on appropriate versus inappropriate prescribing. Aromatase inhibitor (AI) therapy for breast cancer provides an ideal paradigm for studying this issue, because AIs have been the focus of substantial DTCA, and because they should only be used in postmenopausal women, age can serve as a simple surrogate marker of appropriateness.

METHODS

Data regarding national DTCA spending for the AIs were obtained from TNS Multimedia; hormonal therapy prescription data were obtained from IMS Health. Time series analyses were performed to characterize the association between monthly changes in DTCA spending for the AIs and monthly changes in the proportion of all new hormonal therapy prescriptions represented by the AIs from October 2005 to September 2007. Analyses were stratified by age, considering prescriptions for women ≤ 40 (likely premenopausal) to be inappropriate and those for women > 60 (likely postmenopausal) to be appropriate.

RESULTS

Monthly dollars spent on AI-associated DTCA varied considerably ($118,600 to $22,019,660). Time series analysis revealed that for every million dollars spent on DTCA for the AIs, there was an associated increase 3 months later in the new AI prescription proportion of 0.15% for all ages (P < .0001) and 0.18% for those > 60 years (P < .0001), but no significant change for those ≤ 40 at any time from 0 to 6 months.

CONCLUSIONS

DTCA for the AIs was associated with increases in appropriate prescriptions with no significant effect on inappropriate prescriptions, suggesting that DTCA may not foster inappropriate medication use for certain drug classes.

Patient-reported discontinuation of endocrine therapy and related adverse effects among women with early-stage breast cancer

BACKGROUND

Approximately 20% to 50% of women diagnosed with hormone receptor-positive breast cancer discontinue endocrine therapy early; most reports come from automated pharmacy data or small self-report evaluations. We conducted a larger self-report evaluation of endocrine therapy discontinuation associated with patient characteristics and therapy-related adverse effects.

METHODS

We surveyed 538 women from a single health plan who were diagnosed with early-stage breast cancer from 2002 to 2008 and received endocrine therapy. Women reported adverse effects and reasons for discontinuation via mailed survey; tumor characteristics were obtained via registry linkage. We classified women as discontinuers if they self-reported stopping therapy and their self-reported duration of tamoxifen plus aromatase inhibitor (AI) use was < 5 years, and nondiscontinuers if they self-reported ≥ 5 years use or current use. We estimated odds ratios (ORs) with 95% CIs for discontinuation versus continuation by using logistic regression adjusted for age and year of diagnosis.

RESULTS

Among 538 women, 98 (18.2%) discontinued endocrine therapy early. Women with positive lymph nodes (v negative) were significantly less likely to discontinue therapy (odds ratio [OR] = 0.54; 95% CI, 0.31 to 0.93). Almost all women (94%) experienced adverse effects. Experiencing headaches was associated with discontinuation of AIs (OR = 4.16; 95% CI, 2.16 to 8.01) and tamoxifen (OR = 2.34; 95% CI, 1.24 to 4.41); few other individual adverse effects were related to discontinuation despite most discontinuers reporting they "did not like adverse effects" (AIs: 66.7%, tamoxifen: 59.1%).

CONCLUSION

Few individual adverse effects or patient characteristics were significantly associated with endocrine therapy discontinuation, yet adverse effects were prevalent and were the most common reason women reported for discontinuing therapy.

Endocrine therapy initiation from 2001 to 2008 varies by age at breast cancer diagnosis and tumor size

PURPOSE

To evaluate tamoxifen and aromatase inhibitor (AI) initiation over time and by patient characteristics among women diagnosed with breast cancer in a community setting.

METHODS

We conducted a retrospective cohort study of 1,501 women age ≥ 18 years diagnosed with stages I to II invasive, hormone receptor-positive breast cancer from 2001 to 2008 in an integrated delivery system. Using automated pharmacy dispensings, we determined endocrine therapy receipt within 12 months of diagnosis. We used generalized linear models to estimate adjusted relative risks (RRs) with 95% CIs for any endocrine therapy use (v none), tamoxifen use (v none), AI use (v none), and AIs first (v tamoxifen). Each model adjusted for age, stage, body mass index, tumor size, lymph node status, comorbidities, other treatment, and diagnosis year.

RESULTS

Tamoxifen use was at its highest (56.9%) in 2001 and then decreased; AI use was lowest in 2001 (5.5%) and then peaked in 2005 (36.8%). In multivariate models, women age ≥ 65 years were less likely to use any endocrine therapy compared with women age 55 to 64 years (age 65 to 74 years: RR, 0.86; 95% CI, 0.78 to 0.96; age ≥ 75 years: RR, 0.71; 95% CI, 0.61 to 0.81). Women age ≥ 75 years were significantly less likely to begin AIs versus no treatment (RR, 0.46; 95% CI, 0.32 to 0.64) and versus tamoxifen (RR, 0.67; 95% CI, 0.46 to 0.97). Women with tumor sizes 1.0 to 1.9 cm and ≥ 2.0 cm were significantly more likely to use any endocrine therapy compared with women with tumor sizes < 1.0 cm (RR, 1.41; 95% CI, 1.23 to 1.61 and RR, 1.52; 95% CI, 1.27 to 2.81, respectively).

CONCLUSION

Differential initiation over time, as well as by age and tumor size, suggests patient preferences and provider recommendations for endocrine therapy vary, despite guideline recommendations.

An updated review on the efficacy of adjuvant endocrine therapies in hormone receptor-positive early breast cancer

The third-generation aromatase inhibitors (AIS) are largely replacing tamoxifen in the adjuvant treatment of early-stage breast cancer in postmenopausal women with hormone receptor–positive tumours. To date, multiple trials have been conducted comparing tamoxifen treatment with an AI, and all have demonstrated improved disease-free survival with AI treatment. Trials have included direct 5-year comparisons between tamoxifen and an AI, switching to an AI within 5 years after initial tamoxifen treatment, or extending treatment with an AI after 5 years of completed tamoxifen treatment. Some of these trials have been completed; others are ongoing; and head-to-head trial comparisons of individual AIS are also in progress. The present article summarizes the data obtained from various clinical trials of hormonal therapy for early breast cancer. It also reviews recent data so as to shed light on the current status of these therapies. The focus is on the efficacy of treatment with an AI. Toxicity is discussed in the second article in this supplement.

Estrogen stimulation of cell migration involves multiple signaling pathway interactions

Hormone-dependent breast cancers respond to inhibitors of estrogen synthesis or action with tumor regression and with a reduction of new metastases. The mechanisms underlying the effects of estrogen on metastasis likely differ from those on tumor regression. Cell migration is a key first step in the metastatic process. Based on our prior work and other published data, we designed and tested a working model that suggested that estrogen receptor α, epidermal growth factor receptor, focal adhesion kinase (FAK), paxillin, phosphatidylinositol 3 kinase, p60 Src tyrosine kinase (c-Src), c-Jun N-terminal kinase, and MAPK interact to facilitate estradiol (E(2))-induced cell migration. Accordingly, we examined the effect of E(2) on activation of these pathways and demonstrated mechanistic effects by blocking each component and assessing cell migration as a biologic endpoint. Initial studies validated a robust cell migration assay characterized by highly reproducible, dose-dependent responses to E(2). Examining various mechanisms involved in migration, we showed that E(2) induced activation of c-Src, FAK, and paxillin with early peaks within 5-30 min and later peaks at 24 h. ERK and protein kinase B phosphorylation exhibited only early peaks. Blockade of various steps in these signaling pathways with use of small interfering RNA or specific inhibitors demonstrated mechanistic effects of these signaling molecules on cell migration. Our results suggest that the effects of E(2) on cell migration involve multiple, interacting signaling pathways. Important effects are mediated by the MAPK, phosphatidylinositol 3 kinase, and c-Jun N-terminal kinase pathways and use FAK, paxillin, and c-Src for activation. Each pathway represents a potential target for blocking cell migration and metastasis of breast cancer cells.

Influence of Sex Hormones on Cancer Progression

To review the influence of sex hormones on the progression of breast, prostate, gynecologic, and colorectal cancer. The literature was reviewed in an informal manner utilizing the authors' prior knowledge to collate the current evidence for the involvement of sex hormones, particularly estrogens and androgens in the progression of a range of hormonally responsive cancers. In particular, the effect of treatment involving hormone withdrawal treatment was considered strong evidence for involvement. The impact of basal levels of endogenous steroids was considered. Data from clinical trials indicate the efficacy of therapeutic interventions that result in ablation or antagonism of host steroids for a range of cancers. Demonstration of the correlation of the completeness of withdrawal with clinical outcome together with direct evidence of progression from studies looking at the influence of tissue and circulating levels of sex hormones more recently in conjunction with gene expression profiles all provide compelling evidence for the involvement of steroids in the progression of disease. The involvement of steroids in the progression of cancer in hormone-sensitive tissues is well established and an important target for therapy.

Mammostrat as a tool to stratify breast cancer patients at risk of recurrence during endocrine therapy

Introduction

Patients with early-stage breast cancer, treated with endocrine therapy, have approximately 90% 5-year disease-free survival. However, for patients at higher risk of relapse despite endocrine therapy, additional adjuvant therapy, such as chemotherapy, may be indicated. The challenge is to prospectively identify such patients. The Mammostrat^® test uses five immunohistochemical markers to stratify patients on tamoxifen therapy into risk groups to inform treatment decisions. We tested the efficacy of this panel in a mixed population of cases treated in a single center with breast-conserving surgery and long-term follow-up.

Methods

Tissue microarrays from a consecutive series (1981 to 1998) of 1,812 women managed by wide local excision and postoperative radiotherapy were collected following appropriate ethical review. Of 1,390 cases stained, 197 received no adjuvant hormonal or chemotherapy, 1,044 received tamoxifen only, and 149 received a combination of hormonal therapy and chemotherapy. Median age at diagnosis was 57, 71% were postmenopausal, 23.9% were node-positive and median tumor size was 1.5 cm. Samples were stained using triplicate 0.6 mm² tissue microarray cores, and positivity for p53, HTF9C, CEACAM5, NDRG1 and SLC7A5 was assessed. Each case was assigned a Mammostrat^® risk score, and distant recurrence-free survival (DRFS), relapse-free survival (RFS) and overall survival (OS) were analyzed by marker positivity and risk score.

Results

Increased Mammostrat^® scores were significantly associated with reduced DRFS, RFS and OS in estrogen receptor (ER)-positive breast cancer (P < 0.00001). In multivariate analyses the risk score was independent of conventional risk factors for DRFS, RFS and OS (P < 0.05). In node-negative, tamoxifen-treated patients, 10-year recurrence rates were 7.6 ± 1.5% in the low-risk group versus 20.0 ± 4.4% in the high-risk group. Further, exploratory analyses revealed associations with outcome in both ER-negative and untreated patients.

Conclusions

This is the fifth independent study providing evidence that Mammostrat^® can act as an independent prognostic tool for ER-positive, tamoxifen-treated breast cancer. In addition, this study revealed for the first time a possible association with outcome regardless of node status and ER-negative tumors. When viewed in the context of previous results, these data provide further support for this antibody panel as an aid to patient management in early-stage breast cancer.

Type I receptor tyrosine kinases as predictive or prognostic markers in early breast cancer

The type I receptor tyrosine kinase (RTK) family of proteins play an essential role in the progression of early breast cancer. Our understanding of the role of these proteins has increased over the last 20 years, however, as yet, there are still a number of unanswered questions regarding their position in endocrine resistance, chemotherapy resistance and in the biology of breast cancer. There have been, and are currently, a number of clinical trials that have examined the use of anticancer therapy such as cytotoxic drugs, and treatments that target the RTKs and signaling pathways that have been identified. There is clear evidence that molecular subtypes of cancer respond differently to different therapeutic options, which challenges the 'one size fits all' approach to chemotherapy. Here we review the human epidermal growth factor receptor family of proteins and their potential predictive or prognostic role in early breast cancer.

Effects of tamoxifen and exemestane on cognitive functioning of postmenopausal patients with breast cancer: results from the neuropsychological side study of the tamoxifen and exemestane adjuvant multinational trial

PURPOSE

To evaluate the influence of adjuvant tamoxifen and exemestane on cognitive functioning in postmenopausal patients with breast cancer (BC).

PATIENTS AND METHODS

Neuropsychological assessments were performed before the start (T1) and after 1 year of adjuvant endocrine treatment (T2) in Dutch postmenopausal patients with BC, who did not receive chemotherapy. Patients participated in the international Tamoxifen and Exemestane Adjuvant Multinational trial, a prospective randomized study investigating tamoxifen versus exemestane as adjuvant therapy for hormone-sensitive BC.

RESULTS

Participants included 80 tamoxifen users (mean age, 68.7 years; range 51 to 84), 99 exemestane users (mean age, 68.3 years; range, 50 to 82), and 120 healthy controls (mean age, 66.2 years; range, 49 to 86). At T2, after adjustment for T1 performance, exemestane users did not perform statistically significantly worse than healthy controls on any cognitive domain. In contrast, tamoxifen users performed statistically significantly worse than healthy controls on verbal memory (P < .01; Cohen's d = .43) and executive functioning (P = .01; Cohen's d = .40), and statistically significantly worse than exemestane users on information processing speed (P = .02; Cohen's d = .36). With respect to visual memory, working memory, verbal fluency, reaction speed, and motor speed, no significant differences between the three groups were found.

CONCLUSION

After 1 year of adjuvant therapy, tamoxifen use is associated with statistically significant lower functioning in verbal memory and executive functioning, whereas exemestane use is not associated with statistically significant lower cognitive functioning in postmenopausal patients with BC. Our results accentuate the need to include assessments of cognitive effects of adjuvant endocrine treatment in long-term safety studies.

Estrogen receptor signaling in lung cancer

Lung cancer has long been thought of as a cancer that mainly affects men, but over the past several decades, because of the high increase in tobacco use by women, there has been a corresponding dramatic increase in lung cancer among women. Since 1998, lung cancer deaths in women have surpassed those caused by breast cancer in the United States. Annual lung cancer deaths among US women currently surpass those caused by breast, ovarian, and cervical cancers combined. Women are more likely than men to be diagnosed with adenocarcinoma and small cell carcinoma of the lung compared to squamous cell carcinoma, and never-smokers diagnosed with lung cancer are almost three times more likely to be female than male. These observations in the population, coupled to the findings that both estrogen receptors (ERs) and aromatase, the enzyme that synthesizes 17beta-estradiol, are expressed by lung tumors, suggest a role for female steroid hormones in control of lung cancer growth. Preclinical data and clinical data are increasingly emerging to support this concept, and to suggest that a local production of estrogen and expression of ERs occurs in lung tumors that arise in men as well as in women. An additional protein that recognizes 17beta-estradiol with high affinity, GPR30, also is expressed in lung tumors at high levels and may be responsible for some of the proliferation signals induced by estrogen.

Medical oncology: Endocrine-therapy-related symptoms and breast cancer

The association of a treatment-related adverse effect with treatment success has been reported in various clinical situations. The development of vasomotor or joint symptoms is an indication of therapeutic benefit in women receiving endocrine treatment for hormone-receptor-positive breast cancer.

Exemestane: a review of its use in postmenopausal women with breast cancer

Exemestane (Aromasin) is an orally active steroidal irreversible inactivator of the aromatase enzyme indicated as an adjuvant treatment in postmenopausal women with estrogen receptor-positive early-stage breast cancer following 2-3 years of adjuvant treatment with tamoxifen, and for the treatment of advanced breast cancer in postmenopausal women whose disease has progressed following tamoxifen or other antiestrogen therapy. Exemestane is effective for the treatment of postmenopausal women with early-stage or advanced breast cancer. In early-stage disease, switching to exemestane for 2-3 years after 2-3 years of adjuvant tamoxifen treatment was more effective in prolonging disease-free survival than continuing tamoxifen therapy, although it was not associated with an overall survival benefit, except in those with estrogen receptor-positive or unknown receptor status disease when nodal status, hormone replacement therapy (HRT) and chemotherapy use were adjusted for. Moreover, preliminary data suggest that the efficacy of exemestane is generally no different to that of tamoxifen in the primary adjuvant treatment of early-stage breast cancer, although exemestane may be better in prolonging the time to distant recurrence. In advanced disease, exemestane showed equivalent efficacy to megestrol in patients with disease refractory to tamoxifen and an efficacy not significantly different from that of fulvestrant in those refractory to a nonsteroidal aromatase inhibitor. Available data, some of which are limited, suggest exemestane is also effective in the first-line hormonal treatment of advanced breast cancer in postmenopausal women. Exemestane is generally well tolerated, although the potential bone fracture risk of the drug requires further investigation. Results from directly comparative trials indicating the efficacy, tolerability and bone fracture risk of exemestane relative to third-generation aromatase inhibitors and other agents in both early-stage and advanced disease, as well as the optimal sequence of endocrine therapies, are awaited with interest. In the meantime, switching to exemestane should be considered in postmenopausal women who have received 2-3 years of adjuvant tamoxifen treatment for early-stage breast cancer, and is an emerging treatment option for postmenopausal women with advanced breast cancer refractory to one or more antiestrogen therapies.

Long-term estrogen exposure promotes carcinogen bioactivation, induces persistent changes in gene expression, and enhances the tumorigenicity of MCF-7 human breast cancer cells

The cumulative exposure to estrogens is an important determinant in the risk of breast cancer, yet the full range of mechanisms involving estrogens in the genesis and progression of breast cancer remains a subject of debate. Interactions of estrogens and environmental toxicants have received attention as putative factors contributing to carcinogenesis. Mechanistic studies have demonstrated interactions between estrogen receptor alpha (ERalpha) and the aryl hydrocarbon receptor (AhR), with consequences on the genes that they regulate. Many studies of ERalpha and AhR-mediated effects and crosstalk between them have focused on the initial molecular events. In this study, we investigated ERalpha- and AhR-mediated effects in long-term estrogen exposed (LTEE) MCF-7 human breast cancer cells, which were obtained by continuous culturing for at least 12 weeks in medium supplemented with 1 nM of 17beta-estradiol (E(2)). With these LTEE cells and with parallel control cells cultured without E(2) supplementation, we performed an extensive study of cytochrome P450 (CYP) induction, carcinogen bioactivation, global gene expression, and tumorigenicity in immunocompromised mice. We found that LTEE cells, in comparison with control cells, had higher levels of AhR mRNA and protein, greater responsiveness for AhR-regulated CYP1A1 and CYP1B1 induction, a 6-fold higher initial level of benzo(a)pyrene-DNA adducts as determined by liquid chromatography tandem mass spectrometry, marked differences in the expression of numerous genes, and a higher rate of E(2)-dependent tumor growth as xenografts. These studies indicate that LTEE causes adaptive responses in MCF-7 cells, which may reflect processes that contribute to the overall carcinogenic effect of E(2).

Adverse events and bone health during anastrozole therapy in postmenopausal Japanese breast cancer patients

BACKGROUND

Although anastrozole (ANA), an aromatase inhibitor (AI), has been widely used for breast cancer patients; adverse events during ANA therapy in Japanese patients have not been reported.

METHODS

The study included 656 postmenopausal breast cancer patients receiving ANA as postoperative adjuvant therapy in our hospital. Adverse events during ANA therapy, such as musculoskeletal effects and cerebro- and cardiovascular accidents, were investigated over a 5-year period. The percentage changes in lumbar (L2-4) spine bone mineral density (BMD) were determined in 71 patients receiving ANA alone and 26 patients receiving bisphosphonate in combination with ANA for 7-24 months.

RESULTS

The follow-up period ranged from 6 to 60 months (median 23 months). Joint pain, the most common adverse event, was observed in 3.6% (24/656) of the patients. Cerebral infarctions occurred in 0.3% (2/656) of the patients, and no cardiovascular accidents occurred. Bone fractures occurred in nine patients receiving ANA alone. The mean age and BMD of the nine patients were 67.6 years and 71.8% (compared to the young adult mean BMD), respectively. Accumulated and annual fracture rates were 1.3 and 0.8%, respectively. A decrease in BMD was observed in 62.0% (44/71) of the ANA group compared to 26.9% (7/26) of the combination bisphosphonate group (P < 0.01).

CONCLUSION

Incidence of adverse events during AI therapy in this Japanese postmenopausal population appears to be lower than that of the ATAC trial. The incidence of bone fractures during AI therapy is lower in Japan, and the addition of bisphosphonates enhances bone health. We should perform a prospective trial in the future to investigate the precise risk of bone fractures in Japanese patients.

Ratio of 17HSD1 to 17HSD2 protein expression predicts the outcome of tamoxifen treatment in postmenopausal breast cancer patients

PURPOSE

Estrogens have great significance in the development of breast cancer. After menopause, most estrogen biosynthesis is done in peripheral tissue, and the main enzymes involved in balancing the amount of estrone against estradiol are 17beta-hydroxysteroid dehydrogenases (17HSD). The aim of this study was to investigate the prognostic and tamoxifen predictive values of 17HSD1 and 17HSD2 expression.

EXPERIMENTAL DESIGN

Tumors from low-risk breast cancer patients randomized to adjuvant tamoxifen therapy or no adjuvant treatment were analyzed with immunohistochemistry to investigate protein expression of 17HSD1 and 17HSD2 in 912 cases. All patients had lymph node-negative breast cancer and were postmenopausal at the time of diagnosis.

RESULTS

Low 17HSD1 expression was associated with significant benefit from tamoxifen treatment among patients with estrogen receptor (ER)-positive tumors (P < 0.001). For patients with a 17HSD1 score not exceeding that of 17HSD2, tamoxifen increased the rate of distant recurrence-free survival (hazard ratio, 0.37; 95% confidence interval, 0.23-0.60) and breast cancer-specific survival (hazard ratio, 0.30; 95% confidence interval, 0.16-0.54), whereas no apparent effect was observed when the 17HSD1 score was higher than that of 17HSD2. The interaction was significant for both distant recurrence-free survival (P = 0.036) and breast cancer-specific survival (P = 0.014). In the cohort of systemically untreated patients, no prognostic importance was observed.

CONCLUSIONS

This is the first report that clearly distinguishes between the prognostic and predictive importance of 17HSD1 and 17HSD2 in ER-positive breast cancer treated with or without tamoxifen. Our data suggest that the 17HSD1/17HSD2 ratio might be useful as a predictive factor for tamoxifen treatment in ER-positive breast cancer patients.

Inhibition of drug metabolizing cytochrome P450s by the aromatase inhibitor drug letrozole and its major oxidative metabolite 4,4'-methanol-bisbenzonitrile in vitro

PURPOSE

To determine the inhibitory potency of letrozole and its main human metabolite, 4,4'-methanol-bisbenzonitrile, on the activities of eight cytochrome P450 (CYP) enzymes.

METHODS

Letrozole and its metabolite were incubated with human liver microsomes (HLMs) (or expressed CYP isoforms) and NADPH in the absence (control) and presence of the test inhibitor.

RESULTS

Letrozole was a potent competitive inhibitor of CYP2A6 (K (i) 4.6 +/- 0.05 microM and 5.0 +/- 2.4 microM in HLMs and CYP2A6, respectively) and a weak inhibitor of CYP2C19 (K (i) 42.2 microM in HLMs and 33.3 microM in CYP2C19), while its metabolite showed moderate inhibition of CYP2C19 and CYP2B6. Letrozole or its metabolite had negligible effect on other CYPs.

CONCLUSIONS

Based on the in vitro K (i) values, letrozole is predicted to be a weak inhibitor of CYP2A6 in vivo. Letrozole and its major human metabolite show inhibitory activity towards other CYPs, but clinically relevant drug interactions seem less likely as the K (i) values are above the therapeutic plasma concentrations of letrozole.

Vitreo-retinal traction and anastrozole use

PURPOSE

This study tested a prediction stemming from the hypothesis that anastrozole users experience heightened vitreo-retinal traction. This hypothesis was based on the knowledge that menopause increases the risk of intraocular tractional events such as posterior vitreous detachments (PVDs).

METHODS

Retinal thickness was measured for 3 groups of amenorrheic women: (1) anastrozole users and (2) tamoxifen users undergoing adjuvant therapy for early-stage breast cancer, and (3) control subjects not using hormonal medication. Foveal shape indices were derived for subjects without PVDs.

RESULTS

For anastrozole users, the distance to the temporal side of the fovea became less than the distance to the nasal side at a sufficient height above the foveal base. This effect did not exist for control subjects; the between-group difference was appreciable. Results concerning tamoxifen users were inconclusive.

CONCLUSIONS

The foveas of women using anastrozole appear to be subjected to more tractional force than are the foveas of women not using any hormonal medication.