Inclusion Criteria:

- Male or female age (e) of 18 or more.

- Histologically confirmed breast adenocarcinoma, metastatic (measurable or
unmeasurable lesion), HER2 negative (on the last tumor tissue analyzed), Patient to
receive first-line chemotherapy paclitaxel and bevacizumab in a weekly manner as
recommended by the EMEA.

- Hormone receptor status known

- ECOG performance status ≤ 2.

- Life expectancy ≥ 12 weeks.

- Women of childbearing age (except amenorrhea of at least 24 months) must have a
negative pregnancy test serum within 28 days before starting treatment. In the
absence of serum test, a urine pregnancy test (within 7 days before the first dose of
bevacizumab) is required.

- Informed consent form duly signed and dated by patient

Exclusion Criteria:

- Prior chemotherapy for metastatic disease ;

- Concomitant hormone therapy

- The patient must not have undergone radiation therapy for the treatment of metastatic
disease (except cases of analgesic radiotherapy for bone pain due to metastases).

- Pregnant or nursing woman or woman of childbearing age (except amenorrhea for at
least 24 months) who does not use an effective nonhormonal contraceptive method
(intrauterine device, barrier method associated with the use of a spermicidal gel or
surgical castration) for the duration of the study and 6 months after paclitaxel
administration and / or bevacizumab.

- Man who does not accept to use effective contraception during the study period and 6
months after paclitaxel administration and / or bevacizumab.

- Known hypersensitivity to paclitaxel and / or to bevacizumab or to any excipients.

- Patient unable to undergo medical test for geographical, social or psychological
reasons.

- Patient deprived of liberty or placed under the authority of a tutor