Article

Exemestane Versus Anastrozole in Postmenopausal Women With Early Breast Cancer: NCIC CTG MA.27-A Randomized Controlled Phase III Trial

University of Toronto, Toronto
Journal of Clinical Oncology (Impact Factor: 17.88). 01/2013; 31(11). DOI: 10.1200/JCO.2012.44.7805
Source: PubMed

ABSTRACT PURPOSEIn patients with hormone-dependent postmenopausal breast cancer, standard adjuvant therapy involves 5 years of the nonsteroidal aromatase inhibitors anastrozole and letrozole. The steroidal inhibitor exemestane is partially non-cross-resistant with nonsteroidal aromatase inhibitors and is a mild androgen and could prove superior to anastrozole regarding efficacy and toxicity, specifically with less bone loss. PATIENTS AND METHODS
We designed an open-label, randomized, phase III trial of 5 years of exemestane versus anastrozole with a two-sided test of superiority to detect a 2.4% improvement with exemestane in 5-year event-free survival (EFS). Secondary objectives included assessment of overall survival, distant disease-free survival, incidence of contralateral new primary breast cancer, and safety.ResultsIn the study, 7,576 women (median age, 64.1 years) were enrolled. At median follow-up of 4.1 years, 4-year EFS was 91% for exemestane and 91.2% for anastrozole (stratified hazard ratio, 1.02; 95% CI, 0.87 to 1.18; P = .85). Overall, distant disease-free survival and disease-specific survival were also similar. In all, 31.6% of patients discontinued treatment as a result of adverse effects, concomitant disease, or study refusal. Osteoporosis/osteopenia, hypertriglyceridemia, vaginal bleeding, and hypercholesterolemia were less frequent on exemestane, whereas mild liver function abnormalities and rare episodes of atrial fibrillation were less frequent on anastrozole. Vasomotor and musculoskeletal symptoms were similar between arms. CONCLUSION
This first comparison of steroidal and nonsteroidal classes of aromatase inhibitors showed neither to be superior in terms of breast cancer outcomes as 5-year initial adjuvant therapy for postmenopausal breast cancer by two-way test. Less toxicity on bone is compatible with one hypothesis behind MA.27 but requires confirmation. Exemestane should be considered another option as up-front adjuvant therapy for postmenopausal hormone receptor-positive breast cancer.

1 Follower
 · 
399 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: Bone fractures are a major consequence of osteoporosis. There is a direct relationship between serum estrogen concentrations and osteoporosis risk. Aromatase inhibitors (AIs) greatly decrease serum estrogen levels in postmenopausal women, and increased incidence of fractures is a side effect of AI therapy. We performed a discovery case-cohort genome-wide association study (GWAS) using samples from 1071 patients, 231 cases and 840 controls, enrolled in the MA.27 breast cancer AI trial to identify genetic factors involved in AI-related fractures, followed by functional genomic validation. Association analyses identified 20 GWAS SNP signals with p<5E-06. After removal of signals in gene deserts and those composed entirely of imputed SNPs, we applied a functional validation "decision cascade" that resulted in validation of the CTSZ-SLMO2-ATP5E, TRAM2-TMEM14A and MAP4K4 genes. These genes all displayed estradiol (E2)-dependent induction in human fetal osteoblasts transfected with estrogen receptor (ER)α and their knockdown altered the expression of known osteoporosis-related genes. These same genes also displayed SNP-dependent variation in E2 induction that paralleled the SNP-dependent induction of known osteoporosis genes such as osteoprotegerin (OPG). In summary, our case-cohort GWAS identified SNPs in or near CTSZ-SLMO2-ATP5E, TRAM2-TMEM14A and MAP4K4 that were associated with risk for bone fracture in ER-positive breast cancer patients treated with AIs. These genes displayed E2-dependent induction; their knockdown altered the expression of genes related to osteoporosis; and they displayed SNP genotype dependent variation in E2 induction. These observations may lead to the identification of novel mechanisms associated with fracture risk in postmenopausal women treated with AIs.
    Molecular Endocrinology 08/2014; DOI:10.1210/me.2014-1147 · 4.20 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Treatment-emergent symptoms with adjuvant tamoxifen and aromatase inhibitors (AIs) have been associated with superior recurrence-free survival (RFS). We hypothesized that MA.27 anastrozole- or exemestane-treated patients with new or worsening vasomotor and/or joint symptoms would have improved RFS. MA.27 randomly assigned 7,576 postmenopausal women with breast cancer to 5 years of anastrozole or exemestane. Patient-reported symptoms were collected using the Common Terminology Criteria for Adverse Events version 3.0 at protocol-specified baseline and 6- and 12-month clinical visits. Symptoms were considered present with either vasomotor and/or joint complaints. Associations between symptoms and baseline patient characteristics were examined with χ(2) and Fisher's exact tests. Subsequent effects of new or worsening symptoms on RFS were examined with landmark analyses and stratified univariable and multivariable Cox models. We examined the effects of 3-month symptoms arising from unplanned clinic visits as a result of severe toxicity. Patients were assessable if eligible for the MA.27 trial, received some trial therapy, and had no disease recurrence at the end of a symptom assessment period; 96% of patients (n = 7,306 patients) were included at 6 months, and 96% (n = 7,246) were included at 12 months. Thirty-four percent of patients had baseline symptoms. For patients without baseline symptoms, 25% and 52% had new symptoms by 6 and 12 months, respectively. Neither treatment-emergent nor baseline symptoms significantly impacted RFS (P > .10) in patients with or without baseline symptoms. In MA.27, anastrozole or exemestane treatment-emergent symptoms were not associated with improved RFS. Women should be supported through treatment and encouraged to remain on their AI regardless of their symptoms. © 2014 by American Society of Clinical Oncology.
    Journal of Clinical Oncology 12/2014; 33(3). DOI:10.1200/JCO.2014.57.6926 · 17.88 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: 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. 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. 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. 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.
    Current Oncology 03/2015; 22(Suppl 1):S91-113. DOI:10.3747/co.22.2326 · 1.64 Impact Factor