Adjuvant systemic therapies in breast cancer.

Although some women with early breast cancer (BC) may be cured with loco-regional treatment alone, up to 20% of patients with early-stage BC will ultimately experience treatment failure and recurrence. A substantial portion of the success in improving clinical outcomes of patients with BC is related to the standardized use of adjuvant therapies. The identification of tumor subtypes with prognostic value has contributed to the idea of tailoring treatments using biologic predictive factors to identify the patients who will most likely respond to therapy and minimize the exposure of "nonresponders" to the side effects of the treatment.