Inclusion Criteria:

- Femal patient aged > 18 years

- Histologically proven breast cancer

- Menopausal patient according to the following definition:

- amenorrhoea > 1 year or menopause affirmed by a rate of oestradiol or
hypophyseal gonadotrophin

- surgical ovariectomy

- treatment by LHRH analog

- ovarian suppression by radiotherapy

- amenorrhoea induced by chemotherapy > 1 year

- Oestradiol and/or progesterone positive receptors

- Presence of one or several metastatic lesion:

- mesurable lesion

- bone metastase were detected by bone scintigraphy

- Patient who can have received:

- Adjuvant chemotherapy and/or hormonotherapy (Tamoxifen)

- Metastatic Treatment by chemotherapy

- PS < 2

- Adequate biological values

- Patient who has clearly given her consent by signing on informed consent form prior
to participation

Exclusion Criteria:

- Patient previously treated with hormonotherapy in metastatic phase

- Antecedent of treatment with aromatase inhibitors

- local relapse (with the exception of cutaneous thoracic nodes)

- Patient with only one metastatic lesion like: pleurisy , ascites, lung Lymphangitis
carcinomatosa