The purpose of this study is to determine if pharmacokinetics of docetaxel is modified by the body composition (assessed by the BMI but also by CT-scan) in patients treated by docetaxel as adjuvant treatment of a localized breast cancer

Half of the patients treated for a localized breast cancer are obese or overweighted. Recently published post-hoc analyses of a large randomised trial (BIG-2-98) revealed that BMI could impact the benefit of a docetaxel based chemotherapy, but not of an anthracyclin based chemotherapy.

One of the hypothesis is that the distribution volume of hydrophobic drugs, such as docetaxel, may be influenced by the BMI, and more precisely by the amount of total fat.

In that context, we aim to assess the docetaxel pharmacokinetics during its first exposure for localized breast cancer, and compare these results according to 3 groups of patients (lean, overweight and obese).

Inclusion Criteria:

• Woman older than
• Early breast cancer
• CT-scan of less than 3 months, including L3 level
• Indication of docetaxel at 100 mg/m² as adjuvant CT

Exclusion Criteria:

• HER2 amplified or triple negative tumors
• Pregnant or breastfeeding women
• Patients under guardianship or curatorship
• Concomitant administration of another cytotoxic drug or targeted therapy
• Psychosocial disorder
• Administration of another cytotoxic drug or targeted therapy within 20 days prior to blood collection