The evolution of adjuvant endocrine therapy: developments since St Gallen 2005

The most recent Oxford Overview analysis shows that tamoxifen remains a highly effective adjuvant endocrine therapy with continuing benefit for at least 15 years. The aromatase inhibitors (AIs) achieve a further small reduction in recurrence in postmenopausal women either as first-line treatment or sequentially after 2-3 years tamoxifen but so far usually without survival benefit. Differences in side effects are minor and specifically there is no evidence for significant differences in cardiovascular side effects. Extended adjuvant therapy with an AI after 5 years tamoxifen gives important additional protection to women with higher risk cancers. The relative benefits of first-line vs. sequential AIs after 2-3 years tamoxifen await the outcome of current trials. The major outstanding questions include duration of endocrine therapy, the value of ovarian suppression in premenopausal women in addition to other treatments, and the selection of patients who require endocrine therapy alone without additional chemotherapy.