Is long-term adjuvant treatment of breast cancer with anastrozole indicated?

BACKGROUND: Tamoxifen is the established adjuvant treatment for postmenopausal women with hormone-sensitive breast cancer. OBJECTIVE: To determine whether the aromatase inhibitor anastrozole should replace tamoxifen as the adjuvant treatment in this cancer. METHODS: Two recent trials of anastrozole and tamoxifen as adjuvant treatment were evaluated. RESULTS/CONCLUSION: The Arimidex, Tamoxifen, Alone or in Combination (ATAC) trial showed that 5 years of adjuvant therapy with anastrozole reduced recurrence of breast cancer to a greater extent than did tamoxifen. The Austrian Breast and Colorectal Cancer Study Group (ABCSG) Trial 6a showed that after 5 years of adjuvant treatment with tamoxifen more benefit was achieved by continuing with adjuvant anastrozole for 3 years than no further treatment. Although the long-term adjuvant treatment of hormone receptor positive breast cancer with anastrozole is indicated, questions remain as to how long the adjuvant treatment with anastrozole should continue.