Inclusion Criteria:

- Compliant postmenopausal women

- Conservative breast cancer surgery

- Extension evaluation of disease will be proven negative

- Patients with tumor negative margins

- Patients will be classified as T1, T2, T3; Sentinel node negative, N0, N1 or N2; M0.

- Receptor positive tumors (ER and/or PgR = 10 fmol/mg cytosol protein; or = 10% of the
tumor cells positive by immunocytochemical evaluation).

- Adequate marrow function (polynuclear neutrophils >= 1200.10^9/l, platelets >=
100.10^9/l, and hemoglobin >= 10 g/dl).

- Hepatic function (bilirubin >= 30 µmol/l, ALT (SGPT) or AST (SGOT) >= 1.5 x upper
limit of the institution) and cholesterol level <2 x upper limit of the institution.

- Must be geographically accessible for follow-up.

- Written and dated informed consent

Exclusion Criteria:

- Patients with distant metastases.

- Bilateral breast cancer (concomitant or prior) except in situ lesion, either ductal
or lobular, of the contralateral breast.

- Patients staged T4 or N3 or treated by not conservative surgery (radical mastectomy).

- Patients with neoadjuvant chemotherapy or hormonal therapy.

- Patients with previous or concomitant other (not breast cancer) malignancy within the
past 5 years EXCEPT adequately treated basal or squamous cell carcinoma of the skin
or in situ carcinoma of the cervix. Patients who have had a previous other malignancy
must have been disease free for at least five years.

- Patients with other non-malignant systemic diseases (cardiovascular, renal, hepatic,
lung embolism, etc.) which would prevent prolonged follow-up.

- Patients treated with systemic investigational drugs within the past 30 days.

- Breast cancer chemoprevention with anti-estrogens

- Hormone replacement therapy (HRT) not stopped at least 4 weeks before randomization

- Patients known to be HIV positive (no specific tests are required to determine the
eligibility).