Efficacy of anastrozole in a consecutive series of advanced breast cancer patients treated with multiple prior chemotherapies and endocrine agents: M.D. Anderson cancer center experience

Anastrozole is a highly selective, nonsteroidal aromatase inhibitor approved by the U.S. Food and Drug Administration (FDA) in January 1996 for the treatment of advanced breast cancer in postmenopausal women with disease progression following tamoxifen therapy. To date, information on anastrozole's use has been limited to breast cancer patients with minimal prior therapy. The purpose of this review was to determine, in clinical practice, the benefits of anastrozole in advanced breast cancer patients treated with multiple prior cytotoxic and endocrine therapies. This was a retrospective review of a consecutive series of 117 patients who received anastrozole after marketing in January 1996. As this was not a prospective study, rigorous response criteria could not be applied. Responses were categorized as improvement in disease (ID), stable disease (SD), or progressive disease (PD). One hundred eight patients were evaluable for response with a median age of 61 years and the number of prior therapies ranging from one to nine. Response, defined as improvement of disease or stable disease ≥8 weeks, was seen in 59% of patients. Patients with three or more prior endocrine therapies demonstrated a 61% response (ID + SD) and patients with ER-negative tumors demonstrated 50% response. Patients with prior aminoglutethamide therapy exhibited similar response rates to the overall group. One male patient received anastrozole without benefit. This data determines the activity of anastrozole even in heavily pretreated patients and suggests that patients who have tumors that are ER-negative may also benefit from anastrozole therapy.