The objective of the present clinical investigation is to determine whether hormonal therapy given preoperatively is able to reduce tumor size to an extent that facilitates breast-conserving procedures.

This open, prospective multicenter Phase II pilot trial investigates the efficacy of exemestane, 25 mg once daily over 4 months, in postmenopausal women with primary breast cancer, measured in terms of clinical response

Inclusion Criteria:

• Histologically verified breast cancer (punch biopsy), established HER-2/neu status
• Postmenopausal patients (> 1 year following outset of menopause and/or postmenopausal hormonal profile)
• Clinical staging: T2 (> 3 cm), T3, T4a-c, N0-1
• Hormone receptor positivity, i.e. estrogen and/or progesterone receptor > 10 fmol/mg cytosolic protein or ER-ICA-positive and/or PgR-ICA-positive. Positivity of + (low-grade) in one hormone receptor is only eligible in the presence of positivity in the other hormone receptor.
• no internal contraindication
• life expectation > 6 month
• written informed consent

Exclusion Criteria:

• premenopausal patients and patients with no clearly indicated menopausal status
• manifest second malignant tumor (except basalioma or in situ carcinoma of cervix uteri)
• uncontrolled internal disease i.e. diabetes mellitus, cardiac disease (NYHA III/IV)
• thromboembolic disease
• inflammatory mamma carcinoma
• existence of distant metastases
• former or simultaneously therapy with antioestrogens, aromatase inhibitors, cytostatics or radiotherapy
• corticosteroids before and during the study (except inhalant application)
• lack of compliance