Systemic therapy.

The systemic treatment of breast cancer is a moving target, reflected by the continuous update of treatment guidelines. Chemotherapy regimens, including the adjuvant role of taxanes and preoperative systemic therapy, continue to be optimized. A major challenge facing researchers and clinicians is how to improve the therapeutic index of present and future therapies, identify patients most likely to benefit from the proposed intervention, and avoid treating those who would be exposed to potential toxicities with minimal gain. Anti-estrogens are a prime example of a targeted therapy with a high therapeutic index. Data are now available on aromatase inhibitors in the adjuvant setting and pure antiestrogens in metastatic disease. The role of targeted antihuman epidermal growth factor receptor 2 therapy in the adjuvant setting is being actively investigated, but this is complicated by the inadequate standardization of human epidermal growth factor receptor 2 expression assays used in clinical practice. A long overdue revision of the breast cancer staging system becomes effective in January 2003, bringing it more in line with current standards of care and facilitating data collection for future outcome analysis of therapeutic interventions. These and other important developments since 2001 are examined in this review.