Aromatase Intelligence.

Aromatase inhibitors are more effective than tamoxifen (a selective ER modulator) in post-menopausal women. In pre-menopausal women, though, AIs are ineffective due to compensatory ovarian estrogen production–unless they’re on ovarian suppression. This EBCTCG meta-analysis of >7000 women treated in 4 randomized trials compared AIs and tamoxifen in pre-menopausal women receiving ovarian suppression. At 5 and 10 years, AIs reduced breast cancer recurrence by an absolute 3% compared to tamoxifen. There was also a significant reduction in distant recurrence, although there was no difference in breast cancer mortality (at least at 8 years median follow-up). Among subgroups, those with HER2 negative disease derived greater AI benefit while those with 4+ nodes, surprisingly, derived greater benefit from tamoxifen. | EBCTCG, Lancet Oncol 2022