Neoadjuvant tamoxifen and aromatase inhibitors: comparisons and clinical outcomes

Neoadjuvant hormonal therapy for oestrogen receptor (ER) and/or progesterone receptor (PgR) positive large operable or locally advanced breast cancer is effective and a safe alternative to chemotherapy in postmenopausal women. A randomised trial has demonstrated that the response rate and the incidence and degree of downstaging with the aromatase inhibitor letrozole is significantly greater than with tamoxifen [J. Clin. Oncol. 19 (2001) 3808]. Tumours at all levels of ER appear to respond better to letrozole than tamoxifen but at low levels of ER responses are seen only with letrozole and not with tamoxifen. Patients most likely to benefit from neoadjuvant therapy and those who achieve the greatest reduction in tumour volume are those patients with tumours that express very high levels of ER (ALLRED category score 8). Both letrozole and anastrozole appear effective in both erbB2 positive and negative breast cancers. Three months of treatment is adequate to determine if a tumour will respond. Following breast-conserving surgery and radiotherapy, local recurrence rates appear satisfactory.