A topic in Clinical Evidence 1 summarizes the evidence on selective aromatase inhibitors in breast cancer. Several randomised trials were found but no systematic review. Selective aromatase inhibitors (anastrozole, letrozole and vorozole) prolonged survival in postmenopausal women with metastatic breast cancer unresponsive to tamoxifen. Anastrozole increased the median survival with 4 months (from 22.5 to 26.7 months). Adverse effects were minimal as compared to progestin or non-selective aromatase inhibitors. Selective aromatase inhibitors were more effective in oestrogen positive women.
A new steroidal aromatase inhibitor, exemastane, has been studied in phase III clinical trials. It has been superior to progestin in terms of time to disease progression and treatment failure as well as overall survival.
A systematic review 2 including 2 studies with a total of 746 women with breast cancer which had progressed during anti-oestrogen therapy or had relapsed during or after adjuvant tamoxifen therapy was abstracted in DARE. In combined analysis there was a statistically significant survival advantage in the anastrozole 1 mg/day treatment group (median time to death 26.7 months versus 22.5 months in patients treated with megastrol (p<0.025).
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