A Phase II Trial of Neoadjuvant Arimidex With or Without Faslodex in Postmenopausal Women With Hormone Receptor Positive Breast Cancer

Over the last 3 decades, a steady shift has occurred in the management of breast cancer. Because it was traditionally viewed as a local disease, many advocated the use of radical surgery to achieve maximum survival benefit. This view has been slowly replaced by a broader biologic view that recognizes the often systemic nature of breast cancer, even when it appears to be localized to the breast. Results from randomized clinical trials have demonstrated that less extensive surgery, or lumpectomy plus radiation therapy, are optimal for local management of early breast cancer. In addition to the less radical approach to surgical treatment of breast cancer, other randomized clinical trials have established the value of postoperative systemic therapy in improving overall survival by eradicating micrometastatic disease, the major cause of mortality from breast cancer. Despite the well-documented benefits of adjuvant systemic therapy, it is not effective in preventing death from breast cancer in all patients who are candidates for such treatment. The worth of such therapy can only be judged in retrospect upon disease relapse, a time when breast cancer is nearly always incurable. Currently, there are few reliable methods to predict the success or failure of a particular postoperative treatment modality, and better ways to predict and optimize outcome are needed.

Combination endocrine therapy: Using endocrine agents with different mechanisms of action together has the potential advantage of more effectively blocking ER signaling, thus improving the efficacy of such agents against breast cancer. In the past, attempts to combine endocrine agents for ER-positive breast cancer have had mixed results, depending on the setting and the patient population studied.

Endocrine agents without any agonist effect could potentially be used in combination with aromatase inhibitors, under the rationale that the combination would maximally blockade estrogen receptor signaling, thus potentially improving the antitumor effect. Fulvestrant (FASLODEX) is a pure estrogen antagonist with no known agonist effect; thus, it has the potential to provide additional benefit when combined with an aromatase inhibitor. This concept provides the rationale for using the combination of anastrazole and fulvestrant in this study.