• Peter C Dubsky, Raimund Jakesz, Brigitte Mlineritsch, Sabine Pöstlberger, Hellmut Samonigg, Werner Kwasny, Christoph Tausch, Herbert Stöger, Karin Haider, Florian Fitzal, Christian F Singer, Michael Stierer, Paul Sevelda, Gero Luschin-Ebengreuth, Susanne Taucher, Margaretha Rudas, Rupert Bartsch, Günther G Steger, Richard Greil, Lidija Filipcic, and Michael Gnant.
• Medical University of Vienna, Austria.
• J. Clin. Oncol. 2012 Mar 1; 30 (7): 722-8.

PurposeAnastrozole (ANA) alone delivers significant disease-free survival benefits over tamoxifen (TAM) monotherapy in postmenopausal women with early estrogen receptor-positive breast cancer. The ABCSG-8 (Austrian Breast and Colorectal Cancer Study Group 8) study is a large phase III clinical trial addressing the sequence strategy containing ANA in comparison with 5 years of TAM in a low- to intermediate-risk group of postmenopausal patients.Patients And MethodsEndocrine receptor-positive patients with G1 or G2 tumors were eligible. After surgery, patients were randomly assigned to 5 years of TAM or 2 years of TAM followed by 3 years of ANA. Adjuvant chemotherapy and G3 and T4 tumors were exclusion criteria. Intention-to-treat and censored analyses of on-treatment recurrence-free survival (RFS) were performed, and exploratory survival end points and toxicity were investigated.ResultsInformation from 3,714 patients, including 17,563 woman-years, with a median of 60 months of follow-up was available for this analysis. Median age was 63.8 years, 75% were node negative, and 75% had T1 tumors. Sequencing of ANA after identical 2-year treatment with TAM in both arms did not result in a statistically significant improvement of RFS (hazard ratio [HR], 0.80; 95% CI, 0.63 to 1.01; P = .06). Exploratory analyses of distant relapse-free survival indicated a 22% improvement (HR, 0.78; 95% CI, 0.60 to 1.00). On-treatment adverse events and serious adverse events were consistent with known toxicity profiles of ANA and TAM treatment.ConclusionDespite a low overall rate of recurrence in a population with breast cancer at limited risk of relapse, the a priori sequence strategy of 2 years of TAM followed by 3 years of ANA led to small outcome and toxicity benefits.

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