Overview
- An analysis of more than 120 million electronic health records found women using estrogen for at least 10 years before menopause had about 60% lower odds of breast cancer, heart attack and stroke than those who started after menopause or never used it.
- Women who began estrogen after menopause saw smaller benefits and an approximate 4.9% higher likelihood of a cardiovascular event versus never-users, with reports differing on whether this was stroke or heart attack.
- The findings were presented at The Menopause Society meeting, and study authors and society leaders emphasized the limits of observational data and potential biases such as healthy-user effects.
- Independent experts said unanswered questions include which hormone formulations drive the associations, urging prospective or clinical studies to assess causality.
- UK guidance highlights that HRT can slightly increase breast cancer risk and is contraindicated for people with current or past breast cancer, underscoring the importance of individualized decisions.