Breast Cancer and Estrogen Replacement

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Abstract
Bergkvist and colleagues (Aug. 3 issue)1 report that an apparent increased risk of breast cancer was associated with the use of estradiol compounds but not with conjugated estrogens or estriol. Regrettably, they do not state either the dose or the total duration of such treatment in their patients with breast cancer. They also fail to state which estradiol compounds were used, but presumably these were estradiol valerate and ethinyl estradiol, as reported in a previous study of this cohort.2 Clearly the type of estrogen used is of major biologic importance.