XELOX (Capecitabine and Oxaliplatin) is an effective and convenient regimen for patients with metastatic colorectal cancer. Chronomodulated therapy may reduce toxicity. Patients will be randomized to standard XELOX (Capecitabine 1000 mg/m² in the morning and 1000 mg/m² in the evening days 1-14 and short term Oxaliplatin 130 mg/m² day 1 in 30 minutes) or chronomodulated XELOX (Capecitabine 400 mg/m² in the morning and 1600 mg/m² in the evening days 1-14 and short term Oxaliplatin 130 mg/m² day 1 in 30 minutes).

Bloodsamples will be collected and frozen and later examined for potential predictive factors

Inclusion Criteria:

• Histological proven adenocarcinoma of the colon or rectum
• Measurable or non-measurable disease
• Performance status 0-2
• Adequate renal and hepatic functions
• Adjuvant chemotherapy must have ended 180 days before inclusion
• Written informed consent prior to randomization

Exclusion Criteria:

• Prior treatment with Eloxatin or Xeloda
• Peripheral neuropathy
• Evidence of CNS metastasis
• Other serious illness or medical conditions (including contraindication to 5 FU e.g.: angor, myocardial infarction within 6 months)
• Past history of malignant neoplasm within the past five years, except curatively treated non melanoma skin cancer
• Administration of any other experimental drug under investigation within 2 weeks before randomisation
• Pregnant or breast feeding women
• Fertile patients must use adequate contraceptives