The evidence-based use of induction chemotherapy in breast cancer

The use of induction chemotherapy, also known as pre-operative or neoadjuvant chemotherapy has been studied in a number of randomised trials. Response rates are generally high, ranging from 70-90%, which allows for the downstaging of primary tumours and breast conservation surgery. Conserving surgery as opposed to mastectomy in this setting appears to be safe, effective and improves quality of life, although there is a suggestion of a small increase in local recurrence rate. Data from the randomised trials presented in this review shows that the use of induction chemotherapy neither prolongs nor decreases overall or disease free survival when compared with the same chemotherapy given in an adjuvant setting. There is a direct correlation between response of a primary breast tumour to induction chemotherapy and patient outcome, probably because this approximates the effect of induction chemotherapy on micrometastases which are present at presentation in many patients with apparently localised primary breast cancers. A pathological complete response after surgery is an excellent predictor of long term outcome, and is more likely to be seen in smaller tumours. Induction chemotherapy can be used as an in vivo measure of tumour response to treatment. This allows a further option of switching cytotoxic drugs in apparently resistant tumours.