Tamoxifen and Anastrozole as a Sequencing Strategy: A Randomized Controlled Trial in Postmenopausal Patients With Endocrine-Responsive Early Breast Cancer From the Austrian Breast and Colorectal Cancer Study Group

J Clin Oncol. 2012 Mar 1;30(7):722-8. doi: 10.1200/JCO.2011.36.8993. Epub 2012 Jan 23.

Abstract

Purpose: Anastrozole (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 methods: Endocrine 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.

Results: Information 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.

Conclusion: Despite 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.

Publication types

  • Clinical Trial, Phase III
  • Multicenter Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Anastrozole
  • Antineoplastic Combined Chemotherapy Protocols / adverse effects
  • Antineoplastic Combined Chemotherapy Protocols / therapeutic use*
  • Aromatase Inhibitors / administration & dosage
  • Aromatase Inhibitors / adverse effects
  • Aromatase Inhibitors / therapeutic use*
  • Austria
  • Breast Neoplasms / drug therapy*
  • Breast Neoplasms / pathology
  • Breast Neoplasms / surgery
  • Disease-Free Survival
  • Drug Administration Schedule
  • Female
  • Humans
  • Middle Aged
  • Neoplasm Recurrence, Local / pathology
  • Nitriles / administration & dosage
  • Nitriles / adverse effects
  • Nitriles / therapeutic use*
  • Prospective Studies
  • Survival Rate
  • Tamoxifen / administration & dosage
  • Tamoxifen / adverse effects
  • Tamoxifen / therapeutic use*
  • Triazoles / administration & dosage
  • Triazoles / adverse effects
  • Triazoles / therapeutic use*

Substances

  • Aromatase Inhibitors
  • Nitriles
  • Triazoles
  • Tamoxifen
  • Anastrozole