Inclusion Criteria:

- Postmenopausal patients with histologically verified, locoradically treated, invasive
or minimally invasive breast cancer

- Hormone receptor-positive status

- More than 6 histologically examined lymph nodes

- Laboratory parameters

1. hematopoiesis: > 3500/l leukocytes, > 100,000/l thrombocytes

2. renal function: creatinin < 1.5mg%

3. hepatic function: GOT  2.5 x UNL

4. bilirubin: < 1.5mg %

5. metabolic parameters: Na, Ca, K in normal range, normal level of blood sugar

- Concluded healing process following surgery

- Less than 4 weeks interval since surgery

- Informed consent

Exclusion Criteria:

- Premenopausal patients, non-determinable menopausal status

- Previous radiotherapy, chemotherapy or endocrine treatment

- Generalized disease (as verified by lung X-ray, skeletal X-ray, liver ultrasound)

- Contraindications against tamoxifen or anastrozole

- T4 tumors; carcinoma in situ

- Lacking compliance or understanding of disease

- Karnofsky Index < 3

- Serious concomitant disease

- Septic complications, systemic infections or infectious local processes

- Bilateral ovariectomy or ovarian irradiation

- Second carcinoma or status post second carcinoma (except for treated squamous cell
carcinoma of the skin or cervical carcinoma in situ)