Adjuvant drug therapy for operable breast cancer

Breast cancer-the most common malignancy of lethal potential for women in the developed world-presents as two interrelated problems: (1) local disease in the breast and axillary lymph nodes, and (2) micrometastatic disease in distant sites. During the last century, advances in surgery and radiotherapy have led to high rates of control over local disease. In addition, heightened public awareness and the more widespread use of mammography have led to the more frequent detection of smaller cancers with better prognosis. Nevertheless, the problem of distant recurrence, leading almost inevitably to death, persists. Hence, there is considerable interest in integrating systemic therapy, which since mid-century has been shown to be active against advanced disease, into the treatment of primary breast cancer. The long-standing theoretical prediction of benefit from drug therapy as an adjunct to local control procedures has now been confirmed by several decades of clinical investigation. Long-term follow-up of seminal trials and the conduct of a crucial series of meta-analyses have established the ability of both hormonal therapies and chemotherapy to prolong disease-free and overall survival in nearly all groups of patients. Although the relative and absolute influences of drug therapies remain modest, if these were properly applied to the hundreds of thousands of patients diagnosed worldwide per year, the potential impact on public health would be significant. In addition, recent laboratory advances and clinical trial data have indicated several new directions that promise greater impact against occult disseminated disease. These include novel dosing and scheduling strategies, newer active agents, fresh biochemical targets, and different combinations of chemotherapy with hormonal therapy.