Testing "the soft option": trials of adjuvant endocrine therapy for the primary treatment of breast cancer.

Current concepts of the natural history of early breast cancer focus on a belief that for many women the tumor has disseminated prior to the time of diagnosis. For these women systemic treatment is essential to delay or prevent the return of the disease. Results of adjuvant chemotherapy trials indicate a benefit for premenopausal node-positive patients at the expense of toxicity. It is now being recognized that adjuvant endocrine therapy can obtain a similar advantage in a wider range of women with early breast cancer without the severity of side effects. This article seeks to review the role of adjuvant endocrine therapy: "the soft option."