Inclusion Criteria:

- Postmenopausal women who had primary breast cancer, histological confirmed, through a
core needle biopsy, and who{s tumors positive for estrogens receptor ER/PR.

Clinical stage IIB or IIIA Tumor assessable by clinical exam, mammogram or and ultrasound
Adequate functional bone marrow Documented evidence adequate renal function and liver
function Life expectancy for six months Written inform consent

Exclusion Criteria:

- Prior treatment with letrozole or tamoxifen uncontrol disorders patients with
instable angina or uncontrol cardiac disease patient with bilateral breast tumors
patients elegies for conservative breast surgery Inflammatory breast cancer o
distant metastases Other concurrent malignancies, except carcinoma with in situ cono
biopsy of uterine cervix or adequate treat skin cancer no melanoma concomitant
cancer treatment such as chemotherapy, immunotherapy biological modulators,
endocrinotherapy, biphosphonates therapy and radiotherapy.

Concomitant treatment with steroids Others research drug whiting the last 30 days and
concomitant use of research drugs History non compliance with medications schedules and
patients consider potential unreliable.