Exemestane, Letrozole, or Anastrozole in Treating Postmenopausal Women Who Are Undergoing Surgery for Stage II or Stage III Breast Cancer

OBJECTIVES: Primary * Determine whether anastrozole, exemestane, or letrozole administered for 16 to 18 weeks as neoadjuvant endocrine treatment for postmenopausal patients with stage II or stage III estrogen receptor (ER)-positive breast cancer should be chosen as the aromatase inhibitor arm of a future study that will compare neoadjuvant aromatase inhibitor (AI) treatment with neoadjuvant chemotherapy. (Cohort A) * To determine whether patients who have a high Ki-67 value (\> 10%) after 2 weeks of neoadjuvant AI treatment experience a higher than expected pathological response rate to neoadjuvant chemotherapy (20%) than would be typically observed for postmenopausal patients with unselected ER+ rich tumors (estimated to be 5%), indicating that an early assessment of proliferation is a useful approach to the identification of a chemotherapy sensitive subgroup of ER+ tumors. (Cohort B \[patients enrolled after the 375th patient\]) Secondary * Compare the neoadjuvant treatment regimens relative to the rates of improvement in surgical outcome for patients considered marginal for Breast Conservation Surgery prior to therapy. (Cohort A) * Compare the neoadjuvant treatment regimens relative to the rates of improvement in surgical outcome for patients designated as candidates for Mastectomy prior to therapy. (Cohort A) * Compare the relative safety of the neoadjuvant treatment regimens in terms of reported adverse events. (Cohort A) * To compare the tumor pathologic size between the neoadjuvant treatment regimens, to compare the rates of pathological complete response. (Cohort A) * To compare the tumor pathologic size between the neoadjuvant treatment regimens, to compare the rates of down-staging to stage I. (Cohort A) * Compare the incidence of metastatic lymph node involvement on the three arms of the study in patients who have a lymph node dissection at the end of neoadjuvant treatment. (Cohort A) * Compare the neoadjuvant treatment regimens relative to clinical response rate. (Cohort B) * Compare the neoadjuvant treatment regimens relative to progression-free survival. (Cohort A and B) * Compare the neoadjuvant treatment regimens relative to overall survival. (Cohort A and B) OUTLINE: This is a multicenter study comprising cohort A (phase III study) and cohort B (phase II study). Once cohort A accrual is met (375 patients), subsequent patients are enrolled to cohort B. Patients in both cohorts are stratified according to T stage (T2 vs T3 vs T4), and randomized to 1 of 3 aromatase inhibition (AI) treatment arms. * Arm I: Patients receive oral exemestane once daily for 16-18 weeks. * Arm II: Patients receive oral letrozole once daily for 16-18 weeks. * Arm III: Patients receive oral anastrozole once daily for 16-18 weeks. Patients in cohort B undergo breast biopsy after 2-4 weeks of AI treatment for analysis of Ki-67 levels. Patients with Ki-67 level ≤ 10% continue AI treatment. Patients with Ki-67 level \> 10% (high) are given the option to switch to neoadjuvant chemotherapy or undergo immediate breast surgery. After completion of AI therapy, all patients undergo partial or radical mastectomy or lumpectomy with or without lymph node dissection. After surgery, patients are followed up periodically for 10 years. PROJECTED ACCRUAL: A total of 610 patients (375 for cohort A and 235 for cohort B) will be accrued for this study.