Clinico-biological Data Collection Study of Metastatic Breast Cancer

Inclusion Criteria:

1. Written informed consent obtained from the patient prior to performing any protocol-related procedures, including screening biopsy, blood sample, faeces and questionnaires
2. Women \> 18 years old at time of written consent
3. Patient with histologically confirmed breast cancer
4. Breast cancer metastatic disease or locally advanced not eligible for local curative treatment intent with or without personal history of adjuvant therapy for this cancer (chemotherapy, radiotherapy, surgery …)
5. Patient with metastases that can be biopsied.
6. Performance status ≤ 2 (according to WHO criteria)
7. Indication of any systemic therapeutic strategy can be performed alongside this current cohort in accordance with national and / or international recommendations.
8. HR and HER2 status on metastatic sites or breast tumor if local recurrence:

   * For group 1 :

     * Histologic and/or cytological confirmation of estrogen-receptor positive (ER+) and/ or progesterone receptor positive (PR+) breast cancer determined by local laboratory testing
     * No HER2-overexpression in the patient's tumor tissue determined by local laboratory testing
   * For group 2 :

     * Histologic and/or cytological confirmation of estrogen-receptor positive or negative and/ or progesterone receptor positive or negative breast cancer determined by local laboratory testing
     * HER2-overexpression in the patient's tumor tissue determined by local laboratory testing
   * For group 3 :

     * Histologic and/or cytological confirmation of estrogen-receptor negative and progesterone receptor negative breast cancer determined by local laboratory testing
     * No HER2-overexpression in the patient's tumor tissue determined by local laboratory testing
9. Menopausal status : as per the institutional standard of care
10. Patient is willing and able to comply with the protocol for the duration of the study including undergoing treatment and scheduled visits and examinations including follow up.
11. Patient must be affiliated to a Social Health Insurance

Exclusion Criteria:

1. Other malignancy treated within the last 5 years (except non-melanoma skin cancer or in situ carcinoma of the cervix)
2. Coagulopathy or other pathology that contraindicates biopsy procedures
3. Prior systemic treatment in metastatic setting
4. Patients with exclusive brain metastasis not available for surgery
5. Pregnant or nursing patient
6. Individual deprived of liberty or placed under the authority of a tutor
7. Impossibility to submit to the medical follow-up of this clinical trial for geographical, social or psychological reasons