Meta-analysis of trials of aromatase inhibitors versus tamoxifen in post menopausal women with early stage estrogen receptor positive breast cancer has shown that aromatase inhibitors reduce recurrence rates by about 30% comparable tamoxifen over the five-year treatment.
Aromatase inhibitors have not been shown to be efficacious in pre-menopausal women.
Pre-menopausal women treated with ovarian suppression plus aromatase inhibitors had a 3.2% reduced breast cancer risk at five years, with no apparent difference in breast cancer mortality.
Aromatase inhibitors plus ovarian suppression reduced risk of breast cancer recurrence compared with tamoxifen alone in pre-menopausal women.