This study data is actually more reassuring than it appears. What's most striking is how FEW risks there were: no increase in heart disease, stroke, dementia/MCI, diabetes, other cancers (no surprise there), or any other serious condition. The main adverse effects seen here (musculoskeletal) make perfect sense since HRT has consistently been shown to prevent menopausal bone loss and reduce fractures and aromatase inhibitors in breast cancer patients increase fractures, arthritis and arthralgias. The possible link between BSO and sleep apnea or asthma, however, is likely due to loss of progesterone as opposed to estrogen. But altogether, the study challenges the long held dogma that sustained high levels of estrogen throughout life are essential for health maintenance, which they are not.