Lower-Dose vs High-Dose Oral Estradiol Therapy of Hormone Receptor–Positive, Aromatase Inhibitor–Resistant Advanced Breast Cancer

Abstract

The efficacy of a synthetic estrogen, diethylstilbestrol (DES),¹ in the treatment of breast cancer was first described by Haddow et al,² who discussed DES in terms of the wider paradox that certain organic compounds induce cancer but can be used in cancer treatment. Efficacy was restricted to postmenopausal women, suggesting that the decline in estrogen levels associated with menopause may sensitize breast cancer cells to DES.³ Some patients could even be treated with intermittent therapy, with repeated regressions at reintroduction of DES.⁴