The aim of the study is to determine blood concentration evolution of capecitabine and its active metabolites, in elderly patient 75 years and more.

Blood samples will be taken before 1rst course of chemotherapy of capécitabine for colorectal or breast metastatic cancer.

Pharmacokinetic will be realizes at several times (H0,5, H1, H1,5, H2, H4, H6, H8) and repeated at D14 of the 2d cycle

Inclusion Criteria:

• Elderly patients 75 years old or more
• Life expectancy of greater then or equal to 6 months
• Histologically proven metastatic breast or colorectal cancer, requiring a chemotherapy by capecitabine according to the habitual schema
• Metastatic situation whatever treatment line
• Previous hormonotherapy for breast cancer, prior chemotherapy (without capecitabine) in adjuvant and/or metastatic indication (colorectal or breast cancer), or radiotherapy (colorectal or breast cancer) are allowed
• One or more measurable target lesion (RECIST criteria)
• ADL>4 (geriatric scales)
• GSD<12 (geriatric scales)
• Laboratory values :
• creatinine clearance (CrCl) >=30 mL/min according to Cockcroft formula
• Adequate bone marrow function (neutrophils count > 1.5 x 10^9/L, platelets > 100 x 10^9/L, hemoglobin [Hb] > 10g/dl)
• Adequate hepatic function: total bilirubin < 1,5 x upper normal limit, aspartate aminotransferase (ASAT) and alanine aminotransferase (ALAT) < 2,5x upper normal limits (in case of liver metastases < 5 x upper normal limits)
• Alcalin phosphatases <=2,5x ULN (<=5 x ULN if liver metastases present).
• Subjects must be willing to be followed during the course of treatment/observation and follow-up.
• Signed written informed consent before first course of chemotheray

Exclusion Criteria:

• Age < 75 years
• known brain metastases
• Concomitant oncologic treatment ongoing
• History of severe or unscheduled reaction to fluoropyrimidine treatment
• Prior unanticipated severe reaction to capecitabine or metabolites and to fluoropyrimidine therapy
• Patient with leucopenia
• sorivudine or chemical analogues treatment like brivudine
• Physiological, familial, sociological, or geographical conditions that do not permit compliance with the protocol.
• Concomitant severe affections wich lead life expectancy inferior to 3 monthes
• Uncontrolled or symptomatic angina, arrhythmias, or congestive heart failure, coronarian spasmes
• No possible oral administration
• known DPD deficiency
• Treatment with experimental therapy ongoing or within four weeks before inclusion.
• Other cancers within the last five years, with the exception of adequately treated cone-biopsied in situ carcinoma of the uterin cervix or basal or squamous cell carcinoma of the skin