Medical treatment of early breast cancer. IV: neoadjuvant treatment

The main clinical aim of neoadjuvant (also called primary or preoperative) treatment for operable breast cancer before surgery is to downstage large cancers to reduce the need for mastectomy. A research aim is to use the primary tumour as an in vivo measure of responsiveness to treatment. Trials of adjuvant treatments are expensive and take years to complete, and the aim therefore is to use neoadjuvant treatment to find short term surrogate markers (clinical, pathological, or biological) in small trials that can predict long term outcome accurately. For example, in the IMPACT (immediate preoperative Arimidex compared with tamoxifen) trial involving 300 patients, and comparing Arimidex and tamoxifen with the combination, biological changes in tumour proliferation were shown to predict correctly the superiority of adjuvant anastrozole over the other two treatments in the ATAC (Arimidex or tamoxifen alone or in combination) trial, which was a similarly designed adjuvant trial involving 9000 patients. If this can be confirmed in other trials, it may help identify new therapies quickly, and identify optimal treatment for patients.