Tamoxifen and Exemestane Adjuvant Multicenter trial.

1. Histologically/cytologically confirmed adenocarcinoma of the breast, followed by intended curative surgery (R0) and if indicated, also radiotherapy;

2. Any Tumor with a size > 3 cm, or Any N+ or tumor size 1-3 cm, N0 and one of the following factors: MAI > 10, Bloom-Richardson: grade 3, Any TNM stage BC considered to receive adjuvant hormonal therapy, as agreed by NABON-NVMO;

3. ER and/or PgR receptor status positive;

4. Post-menopausal defined as:

a. Age ³ 50 and amenorrhea for > 1 year;

b. Bilateral surgical oophorectomy (and no HRT) (any age is acceptable);

c. Age < 50 with natural amenorrhea > 1 year at breast cancer diagnosis (and uterus in situ) In case of doubt about subject’s menopausal status, FSH assessments have to be performed to define the menopausal status (FSH should be in the postmenopausal range according to values of the local institution);

5. Adequate hematological-, renal- and hepatic function (defined as PLT > 100x109/L, WBC > 3x 10 9/L, Creatinine< 1.5 UNL and SGOT (ASAT) or SGPT (ALAT) < 2.5 UNL);

6. Accessible for follow-up for the duration of the trial;

7. ECOG performance status 0 or 1;

8. Written informed consent (according to ICH/GCP and local IRB guidelines);

9. Baseline clinical laboratory tests are done within 4 weeks prior to randomization;

10. Adjuvant hormonal treatment is started within 10 weeks after completion of surgery (date of tumor removal or re-excision) or date of last adjuvant chemotherapy.

1. Inflammatory breast cancer, positive supraclavicular nodes, ulceration/infiltration of local skin metastasis;

2. Both ER negative and PgR negative primary tumor;

3. Evidence of distant metastases (M1);

4. Patients who have received previous hormonal treatment as adjuvant treatment for breast cancer;

5. Uncontrolled cardiac disease including unstable angina, CHF or arrhythmia requiring medical therapy or with a history of myocardial infarction within the past 3 months or any other serious concomitant disease.;

6. Psychiatric disorders preventing proper informed consent;

7. Tumor with a size < 1cm and N0;

8. Tumor size 1-3 cm, N0 without additional risk factors;

9. Concomitant malignancies except for adequately treated carcinoma in situ of the uterine cervix or basal squamous cell carcinoma of the skin, unless agreed by the Steering Committee. Subjects with other malignancies must be disease-free for at least 5 years. Patients with a history of breast cancer should be excluded;

10. Concurrent participation in another clinical study that may interfere with the results of the trial involving investigational agents within thirty days of treatment from this study, unless this is agreed by both the Steering Committee and the Coordinating Investigator of the study involved;

11. Other serious illnesses that may interfere with subject compliance, adequate informed consent or determination of causality of adverse events;

12. Hormone replacement therapy for treatment of menopausal symptoms that was not stopped at least 4 weeks prior to randomization;

13. Patients who were treated with neo-adjuvant chemotherapy;

14. Patients with a bilateral tumor.