Preoperative hormone therapy trials for breast cancer

Preoperative hormone therapy for breast cancer has the potential to downstage a primary tumour hence increasing operability as well as making breast conservation feasible. Whether it will achieve any clinically significant survival benefit remains to be elucidated. Preoperative hormone therapy, in contrast to neoadjuvant chemotherapy, produces less severe side effects and can be continued throughout the perioperative period. Pre-surgical studies have demonstrated anti-tumour effects of hormone therapy, e.g. down-regulation of ER. Current clinical trials have shown that, in patients with ER positive tumours, a response approaching 70% is reached in approximately three months using the traditional hormonal agent tamoxifen. The tumour seldom progresses during this period. New agents (such as third generation aromatase inhibitors and pure anti-oestrogens) may produce more profound and rapid responses. Future trials are required to identify factors other than ER to precisely predict response so that appropriate patients can be selected. The best agents, the ideal methods of monitoring response and the optimum duration of therapy also need to be identified. Clinical trials also need to test if pre- and perioperative hormone therapy is superior to conventional adjuvant hormone therapy in patients with early breast cancer.