Phase II Trial of Anastrozole Plus Goserelin in the Treatment of Hormone Receptor–Positive, Metastatic Carcinoma of the Breast in Premenopausal Women

To explore the antitumor activity of the aromatase inhibitor, anastrozole, in the treatment of premenopausal women with hormone receptor-positive, metastatic breast cancer who have been rendered functionally postmenopausal with the use of the luteinizing hormone-releasing hormone agonist, goserelin. Premenopausal women with estrogen and/or progesterone receptor-positive, metastatic or recurrent breast cancer were enrolled in this prospective, single-arm, multicenter phase II trial. Patients were treated with goserelin 3.6 mg subcutaneous monthly and began anastrozole 1-mg daily 21 days after the first injection of goserelin. Patients continued on treatment until disease progression or unacceptable toxicity. Thirty-five patients were enrolled of which 32 were evaluable for response and toxicity. Estradiol suppression was assessed, with mean estradiol levels of 18.7 pg/mL at 3 months and 14.8 pg/mL at 6 months. One participant (3.1%) experienced a complete response, 11 (34.4%) experienced partial response, and 11 (34.4%) experienced stable disease for 6 months or longer for a clinical benefit rate of 71.9%. Median time to progression was 8.3 months (range, 2.1 to 63+) and median survival was not been reached (range, 11.1 to 63+). The most common adverse events were fatigue (50%), arthralgias (53%), and hot flashes (59%). There were no grade 4 to 5 toxicities. The combination of goserelin plus anastrozole has substantial antitumor activity in the treatment of premenopausal women with hormone receptor-positive metastatic breast cancer.