Twenty patients with verified high risk breast cancer will be included in the study. Patients will receive three cycles of docetaxel followed by three cycles of CEF for their adjuvant treatment. The phenotype of CYP3A and the genotype of CYP3A5 and MDR1 will be assessed. Also the effect of docetaxel in the activity of CYP3A will be measured by peroral midazolam.

Primary Object:

The primary object of this study is to define, if it is possible to predict the clearance and/ or toxicity of docetaxel by assessing

• activity of CYP3A4 by midazolam test (CYP3A4 phenotype)
• CYP3A5 genotype
• MDR1 genotype

Secondary object:

The secondary object of this study is to define whether the treatment with docetaxel alters the activity of CYP3A4 enzyme in previously untreated breast cancer patients.

Inclusion Criteria:

Subjects may be included in the study only if they meet all of the following criteria:

1. The patient has received information on the purpose of the study and the meaning of the treatment, and has given verbal and written consent to participate in the study. The patient is accessible for treatment and follow-up.
2. Histologically verified diagnosis of breast cancer
3. High risk for recurrence ( node positive or node negative if T2 with histological grade 2 or 3, or Pgr negative)
4. No metastases
5. Females, age =<60
6. No concomitant regular medication which is either substrate, inducer or inhibitor of CYP3A4

Exclusion Criteria:

Subjects will be excluded from the study for any of the following reasons:

1. Poor performance status,>=2 according to WHO

2. Inadequate bone marrow reserve defined as:

   • hemoglobin < 100 g/L
   • leukocytes < 3.0 x 10E9/L or neutrophiles < 1.5 x 10E9/L
   • plateless < 120 x 10E9/L

3. Inadequate liver function defined as:

   • ALAT is > 1.5 x units of normal level
   • elevated bilirubin (unless verified Gilbert´s syndrome)
   • alkaline phosphatase is > 2.5 x units of normal level

4. History of concomitant serious physical or psychiatric disease, which makes a regular cytotoxic treatment impossible

5. cardiac insufficience; severe arrhythmia; severe hypertension; cardiac infarction within one year or other active cardiac disease

6. pregnant or lactating patients

7. abuse of alcohol or any narcotic substances

Twenty patients with verified high risk breast cancer.