The scientific value of preoperative studies and how they can be used

Preoperative hormonal therapy appears to be an effective option for the treatment of breast cancer and this treatment approach enables breast conservation surgery to be performed instead of mastectomy in patients with large, operable tumors. Short-term preoperative trials are valuable for research of established agents where differential efficacy in biologically distinct subgroups is to be investigated. They can be used to generate hypotheses that can be further examined in suitably powered clinical trials. Longer-term 'therapeutic trials', in which surgery is delayed over a period of months, not only allow for a reduction in tumor size with treatment, but also provide an opportunity to perform a detailed analysis of biomarker expression. Recent advances in hormonal preoperative studies and the increasing importance of prognostic and predictive factors in the management of patients with breast cancer are discussed in this review. Indeed, several clinical studies have been performed in the preoperative setting and it is now apparent that the aromatase inhibitors, such as letrozole ('Femara') and anastrozole ('Arimidex'), are valid new treatment options at this stage of treatment.