The new millennium for adjuvant therapy in breast cancer

The treatment of microscopic metastatic breast cancer with adjuvant systemic therapy has undergone significant changes in recent years. At the same time, our understanding of the biology of breast cancer has also improved, predominantly as a consequence of data obtained from cDNA microarrays. Breast cancer genomic analyses now suggest that current breast cancer systemic therapies have a profound biologic basis, and further suggest the possibility that adjuvant therapies can be administered with increasing efficacy and safety. This article reviews recent advances in adjuvant systemic therapy, places these advances in the context of our improving understanding of breast cancer biology, and addresses current research questions for the main categories of breast cancer.