Adequacy of estrogen suppression with aminoglutethimide and hydrocortisone as treatment of human breast cancer: correlation of hormonal data with clinical responses.

Human breast neoplasms can be divided into hormone-dependent and hormone-independent subtypes. Estrogen is the major hormonal stimulus for growth of the dependent tumors. Failure to respond to estrogen suppression therapy could reflect either an incomplete lowering of estrogens or the hormonal independence of the tumor. To address this issue, we compared the levels of several estrogens and other hormones in women experiencing objective responses (the responders) and disease progression (the progression group) during therapy with the aromatase-steroidogenesis inhibitor, aminoglutethimide, and replacement hydrocortisone. Pretreatment hormonal profiles of the estrogens, and androgens, ketosteroids, thyroxine, polypeptide hormones, and carcinoembryonic antigen did not differ significantly among response groups. During treatment, the levels of all estrogens were suppressed to a similar degree in the progression group and in the responders. Urinary estrone, for example, fell to 16.7 +/- 3.2% of basal in the responders versus 16.3 +/- 3.8% of basal in the progression group. These data suggested that lack of estrogen suppression did not explain the response to treatment in the patients receiving aminoglutethimide-hydrocortisone. This finding differs from our results in a similarly analyzed control group of patients treated with surgical adrenalectomy. Levels of the weak androgens, dehydroepiandrosterone sulfate and androstenedione, were found to be higher in the progression group compared to the responders. This observation could not be explained by differences in duration of treatment between groups. Analysis at 1 to 12 weeks, 13 to 24 weeks, and 25 to 36 weeks after initiating treatment indicated higher androgen levels at each time point in the progression group. In addition, the results were not attributable to differing serum levels of aminoglutethimide among responder groups. While the finding of higher androgen levels in the responder group remains unexplained, this study indicates that incomplete estrogen suppression is not responsible for lack of tumor response in patients with progressive disease during amino-glutethimide-hydrocortisone therapy.