Randomized Trial of Tamoxifen Versus Tamoxifen Plus Aminoglutethimide as Adjuvant Treatment in Postmenopausal Breast Cancer Patients With Hormone Receptor-Positive Disease: Austrian Breast and Colorectal Cancer Study Group Trial 6

Purpose: To determine whether the addition of aminoglutethimide to tamoxifen is able to improve the outcome in postmenopausal patients with hormone receptor–positive, early-stage breast cancer. Patients and Methods: A total of 2,021 postmenopausal women were randomly assigned to receive either tamoxifen for 5 years alone or tamoxifen in combination with aminoglutethimide (500 mg/d) for the first 2 years of treatment. Tamoxifen was administered at 40 mg/d for the first 2 years and at 20 mg/d for 3 years. Results: All randomized and eligible patients were included in the analysis according to the intention-to-treat principle. After a median follow-up of 5.3 years, the 5-year disease-free survival in the aminoglutethimide plus tamoxifen group was 83.6% versus 83.7% in the monotherapy group (P = .89). The corresponding data for overall survival at 5 years were 91.4% and 91.2%, respectively (P = .74). More patients failed to complete combination treatment (13.7%) because of side effects as compared to tamoxifen alone (5.2%; P = .0001). Conclusion: Aminoglutethimide given for 2 years in addition to tamoxifen for 5 years does not improve the prognosis of postmenopausal patients with receptor-positive, lymph node-negative or lymph node-positive breast cancer.