Standard administration of capecitabine use a 14 days administration. Routine practice in several intitution leads to use a 5 out of 7 days regimen, with less toxicity.

Purpose : to compare the pharmacokinetics of capecitabine, administered 5 days out of 7, as compared to the standard administration (14 days out of 21). The second end point is to compare toxicity with either regimen.

Method : Randomized study with two groups : one with standard administration , the second with 5/7 days regimen

Inclusion Criteria:

• Histologically proven breast adenocarcinoma
• Evaluable or measurable metastases
• HER-2 status 0 or 1 in immnohistochimy or negative in FISH/CISH
• Previously treated with anthracyclines and taxanes
• Age > = 18 y
• No more than two previous chemotherapy regimens for metastases
• No nervous central system involvement
• Hormonal therapy must have been stopped two weeks before enrollment
• Adequate biologic function
• Performance status OMS < = 2
• Signed informed consent

Exclusion Criteria:

• History of other malignancies, except basocellular cancer, in situ cervix carcinoma
• Gastro intestinal disease that might affect absorption of capecitabine
• Cardiac failure or angina pectoris uncontrolled
• Hypersensitivity for capecitabine, fluorouracil, or one of their excipient
• Known dihydropyrimidine dehydrogenase (DPD) deficiency
• Concomitant anticancer therapy (included hormonotherapy)
• Concomitant radiotherapy
• Treatment with sorivudine and analogs
• Pregnant or breast feeding patients. Contraception methods excluding hormonal treatment is required.
• Inclusion in an experimental protocol within 30 days