Optimal Duration of Pre-operative Treatment With Letrozole and to Correlate Clinical Efficacy With Appropriate Surrogate Markers

Exclusion Criteria

• •1. Prior treatment with aromatase inhibitors or antiestrogens.
• •2. Uncontrolled endocrine disorders such as diabetes mellitus, confirmed hypo- or hyperthyroidism, Cushing´s Syndrome, Addison´s disease (treated or untreated), Patients with unstable angina, uncontrolled cardiac disease (e.g. Class II or IV New York Heart Association's Functional Classification).
• •3. Patients with tumors in both breasts, evidence of inflammatory breast cancer or distant metastasis
• •4. Patients who are eligible for breast conserving surgery.
• •5. Concomitant anti-cancer treatments such as chemotherapy, immunotherapy/biological response modifiers (BRM's), endocrine therapy (including steroids), bisphosphonate therapy and radiotherapy. Patients who have received HRT will NOT be excluded, provided that HRT is discontinued at least 2 weeks prior to entry into the study.