Meta-analysis of trials comparing anastrozole and tamoxifen for adjuvant treatment of postmenopausal women with early breast cancer.

Adnan Aydiner,Faruk Tas

doi:10.1186/1745-6215-9-47

Abstract

ObjectiveIt was aimed to review the literature and make a meta-analysis of the trials on both upfront, switching, and sequencing anastrozole in the adjuvant treatment of early breast cancer.MethodsThe PubMed, ClinicalTrials.gov and Cochrane databases were systematically reviewed for randomized-controlled trials comparing anastrozole with tamoxifen in the adjuvant treatment of early breast cancer.ResultsThe combined hazard rate of 4 trials for event-free survival (EFS) was 0.77 (95%CI: 0.70–0.85) (P < 0.0001) for patients treated with anastrozole compared with tamoxifen. In the second analysis in which only ITA, ABCSG 8, and ARNO 95 trials were included and ATAC (upfront trial) was excluded, combined hazard rate for EFS was 0.64 (95%CI: 0.52–0.79) (P < 0.0001). In the third analysis including hazard rate for recurrence-free survival (excluding non-disease related deaths) of estrogen receptor-positive patients for ATAC trial and hazard rate for EFS of all patients for the rest of the trials, combined hazard rate was 0.73 (95%CI: 0.65–0.81) (P < 0.0001).ConclusionAnastrozole appears to have superior efficacy than tamoxifen in the adjuvant hormonal treatment of early breast cancer. Until further clinical evidence comes up, aromatase inhibitors should be the initial hormonal therapy in postmenopausal early breast cancer patients and switching should only be considered for patients who are currently receiving tamoxifen.

Highlights

The standard treatment of early breast cancer is surgery, with or without radiotherapy and chemotherapy, followed by hormonal therapy for women with hormone receptor-positive tumors
5 years of tamoxifen has been the mainstay of adjuvant hormonal therapy for more than 20 years [1], tamoxifen is associated with treatment resistance [2] and some serious adverse events, like endometrial carcinoma and thromboembolic complications [3]
The remaining 6 publications were the results of 4 different studies, which are ATAC [4], Italian Tamoxifen Anastrozole (ITA) [8], ABCSG 8 [12], and ARNO 95 [13] trials

Summary

Introduction

The standard treatment of early breast cancer is surgery, with or without radiotherapy and chemotherapy, followed by hormonal therapy for women with hormone receptor-positive tumors. Recent findings from large randomized trials have shown that anastrozole, a third generation aromatase inhibitor, has higher efficacy in terms of lower recurrence rates and better safety profile than tamoxifen as adjuvant therapy in early breast cancer [4,5,6,7,8,9]. Trials 2008, 9:47 http://www.trialsjournal.com/content/9/1/47 hormone-sensitive early breast cancer, and that optimal treatment should include an aromatase inhibitor to reduce the risk of tumor recurrence [10]. There are several studies on the advantages of anastrozole over tamoxifen as adjuvant hormonal therapy of hormone-sensitive early breast cancer, the timing and duration of anastrozole treatment remains in question. All approaches have shown a superior efficacy and safety of anastrozole over tamoxifen

Methods

Results

Discussion

Conclusion