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.