Study of High-dose Letrozole Therapy in Postmenopausal Patients With Breast Cancer

Inclusion Criteria: * Patients with histologically documented breast cancer. * Patients with hormone receptor (ER and/or PgR) status of positive or unknown * Patients who have been amenorrheic for the preceding 12 months or more. * Patients who are 20 years or older and younger than 75 years. * Patients with a history of postoperative adjuvant therapy or a history of endocrine therapy with tamoxifen for the treatment of progression or recurrence of the lesion. The endocrine therapy, however, should not exceed one regimen. * Patients with progressing lesions. * Patients with sufficient organ function to evaluate the safety * Patients whose performance status (PS) is classified in 0～2. * Patients who have no residual effects from previous treatments Exclusion Criteria: * Patients with other concurrent or previous malignant disease (excluding uterine carcinoma in-situ). * Patients with hypercalcemia and uncontrollable cardiac disease (including a history of serious cardiac disease) * Patients who have previously received aromatase inhibitor. * Patients who have lymphangitis-type lung metastasis or symptomatic brain metastasis. Other protocol-defined inclusion / exclusion criteria may apply.