Fulvestrant and/or Anastrozole in Treating Postmenopausal Patients With Stage II-III Breast Cancer Undergoing Surgery

Overview

The study is being conducted to determine whether neoadjuvant endocrine therapy with fulvestrant or the combination of anastrozole and fulvestrant, is better than anastrozole when given before surgery to shrink the cancer and stop it from growing. Anastrozole inhibits tumor growth by reducing the levels of estrogen and has been approved by the Food and Drug Administration (FDA) of the United States for use after surgery for postmenopausal women with estrogen receptor positive breast cancer. It is also considered a standard of care to give anastrozole for a few months before surgery to shrink the tumor. Fulvestrant inhibits tumor cell growth by reducing the levels of estrogen receptor in the tumor cell. It is not approved by the FDA for use in women with early stage breast cancer before or after surgery, but is approved by the FDA for patients with advanced (Stage 4) estrogen receptor positive breast cancer that has spread to other parts of the body.

This clinical trial was designed to examine the pathologic outcomes of patients whose neoadjuvant treatment course is determined using an early marker of endocrine resistance (namely, Ki67 after 4 or 12 weeks of neoadjuvant therapy) as well as assessing clinical outcome of patients whose disease burden after completing neoadjuvant endocrine therapy is classified as Modified PEPI 0. The primary and secondary objectives for the study are described below. Primary Objectives: 1. To determine whether fulvestrant administered for 24 weeks as neoadjuvant endocrine treatment decreases the proportion of endocrine resistant tumors\* relative to patients treated with anastrozole. 2. To determine whether fulvestrant in combination with anastrozole, administered for 24 weeks as neoadjuvant endocrine treatment, decreases the proportion of endocrine resistant tumors\* relative to patients treated with anastrozole. 3. To assess whether the 5 year RFS rate among women with a modified preoperative endocrine prognostic index (PEPI) score of 0 following 24 weeks of neoadjuvant anastrozole treatment is at least 95%. 4. To assess whether the 5 year RFS rate among women with a modified PEPI score of 0 following 24 weeks of neoadjuvant fulvestrant, or fulvestrant in combination with anastrozole, is at least 95%. Note that this objective will only be tested if the selected fulvestrant arm was shown to be superior to anastrozole in objective 1 or 2. Endocrine resistant tumor is defined by any one of the following criteria\*: * Ki67\> 10% after 4 weeks on neoadjuvant endocrine therapy * Ki67\> 10% after 12 weeks on neoadjuvant endocrine therapy * Progressive disease is documented anytime during neoadjuvant endocrine therapy * Surgical findings at 22-24 weeks post neoadjuvant endocrine therapy are such that: * pT stage is 3/4 * positive lymph nodes are present or Ki67 \> 2.7% (ie modified PEPI score of not being 0) * Discontinued neoadjuvant endocrine treatment for any reason Secondary Objectives: 1. To assess whether the 5 year RFS rate among women with a preoperative endocrine prognostic index PEPI score of 0 following 24 weeks of neoadjuvant anastrozole treatment is at least 95%. 2. To examine the differences in surgical outcome, clinical and radiological response rates, and safety profile between the fulvestrant arm and the anastrozole arm. 3. To examine the differences in surgical outcome, clinical and radiological response rates, and safety profile between patients randomized to fulvestrant in combination with anastrozole and those randomized to anastrozole. 4. To examine the rate of pathologic complete response (pCR) of 12 weeks of neoadjuvant paclitaxel in patients with endocrine resistant disease following 4 weeks or 12 weeks of neoadjuvant endocrine therapy (with either fulvestrant or anastrozole or the combination of fulvestrant and anastrozole). 5. To examine the rate of pathologic complete response (pCR) among those patients with endocrine resistant disease, following 4 weeks or 12 weeks of neoadjuvant endocrine therapy (with either fulvestrant or anastrozole or the combination of fulvestrant and anastrozole), who choose not to receive neoadjuvant paclitaxel, but another standard neoadjuvant taxane and/or anthracycline containing regimen or CMF. 6. To summarize the frequency of severe (NCI CTCAE grade \> 3) adverse events encountered with administration of paclitaxel in the neoadjuvant setting. 7. To assess RFS for patients with endocrine resistant tumors defined as: 1) Ki67 \> 10% at week 4, 2) Ki67 \> 10% at week 12 and 3) modified PEPI score of non-zero on neoadjuvant endocrine therapy, with all three groups combined or separated.