Aromatase inhibition with 4-hydroxyandrostenedione in the treatment of postmenopausal patients with advanced breast cancer: a phase II study.

Estrogen deprivation by aromatase inhibition is an effective treatment in breast cancer. Between October 1986 and March 1988, 91 postmenopausal patients with advanced breast cancer entered a phase II study performed jointly in three center to investigate the new aromatase inhibitor 4-hydroxyandrostenedione. Patients received 500 mg 4-hydroxyandrostenedione intramuscularly (IM) every 2 weeks for 6 weeks, and 250 mg every 2 weeks thereafter. There were two complete (CRs) and 19 partial remissions (PRs) (response rate, 23%). Disease stabilization (no change; NC) was seen in 26 patients, and in 44 patients (48%), disease progression occurred. Duration of the CRs is 20+ months, median durations of PR and NC are 13+ and 8 months, respectively. Receptor status, relapse-free interval, and sites of metastatic lesions did not appear to influence treatment results. However, efficacy of previous tamoxifen treatment favorably predicted response to 4-hydroxyandrostenedione. Serum estradiol levels decreased significantly in patients after 2 weeks of treatment. Side effects were mostly nonspecific and of low degree, requiring discontinuation of treatment in only 3% of the patients. We conclude that aromatase inhibition with 4-hydroxyandrostenedione is efficacious in the treatment of postmenopausal breast cancer.