Systemic adjuvant therapy has become a regular part of the treatment for patients with potentially curable breast cancer. At the same time radiotherapy has declined in popularity as an adjunct to mastectomy and has taken on a new role in breast conservation. Although systemic therapy has improved the prognosis for breast cancer, numerous issues, such as the optimal combination and dosage of drugs, the worth of chemohormonotherapy and the appropriate sequencing of treatment, remain the subjects of continuing investigation.