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

A Randomized Phase III Trial Comparing 16 to 18 Weeks of Neoadjuvant Exemestane (25 mg Daily), Letrozole (2.5 mg), or Anastrozole (1 mg) in Postmenopausal Women With Clinical Stage II and III Estrogen Receptor Positive Breast Cancer

RATIONALE: Estrogen can cause the growth of breast cancer cells. Hormone therapy using exemestane, letrozole, or anastrozole, may fight breast cancer by lowering the amount of estrogen the body makes. Giving exemestane, letrozole, or anastrozole before surgery may make the tumor smaller and reduce the amount of normal tissue that needs to be removed. It is not yet known whether exemestane, letrozole, or anastrozole is more effective in treating breast cancer.

PURPOSE: This randomized phase III trial is studying exemestane, letrozole, and anastrozole to compare how well they work 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.

DISEASE CHARACTERISTICS:

• Diagnosis of breast cancer

  • T2-T4c, any N, M0 disease

• Clinically staged, as documented by the treating physician, as 1 of the following:

  • T4a-c disease for which modified radical mastectomy with negative margins is the goal
  • T2 or T3 disease for which conversion from needing mastectomy to breast conservation is the goal
  • T2 disease for which lumpectomy at first attempt is the goal

• Primary tumor must be palpable and measure > 2 cm by tape, ruler, or caliper measurements in at least one dimension

• Must agree to undergo mastectomy or lumpectomy after neoadjuvant aromatase inhibitor therapy

• No inflammatory breast cancer, defined as clinically significant erythema of the breast and/or documented dermal lymphatic invasion (not direct skin invasion by tumor or peau d'orange without erythema)

• No distant metastasis (M1)

  • Isolated ipsilateral supraclavicular node involvement allowed

• No diagnosis that was established by incisional biopsy

• Must have estrogen receptor (ER) positive tumor with an Allred score of 6, 7 or 8

  • Patients with > 66.66% (two-thirds) of cells staining positive and have a minimum Allred score of 6 are eligible

PATIENT CHARACTERISTICS:

• ECOG/Zubrod performance status of ≤ 2

• Female

• Patient must be postmenopausal, verified by 1 of the following:

  • Bilateral surgical oophorectomy
  • No spontaneous menses ≥ 1 year
  • No menses for < 1 year with FSH and estradiol levels in postmenopausal range

• No other malignancies within the past 5 years, except for successfully treated cervical carcinoma in situ; lobular carcinoma in situ of the breast; contralateral ductal carcinoma in situ that was treated with mastectomy or lumpectomy with radiotherapy (without tamoxifen); or non-melanoma skin cancer with no evidence of recurrence

  • Must have undergone potentially curative therapy for all prior malignancies AND deemed to be at low risk for recurrence, according to the treating physician

PRIOR CONCURRENT THERAPY:

• No prior treatment for invasive breast cancer, including radiotherapy, endocrine therapy, chemotherapy, or investigational agents
• No prior sentinel lymph node biopsy (cohort B only)
• At least 1 week since prior agents with estrogenic or putatively estrogenic properties, including herbal preparations
• At least 1 week since prior hormone replacement therapy of any type, megestrol acetate, or raloxifene
• No concurrent enrollment in another neoadjuvant clinical trial for treatment of the existing breast cancer
• No other concurrent anti-neoplastic therapy, including chemotherapy or radiotherapy
• No concurrent agents or herbal products that alter ER function