Efficacy and Safety Study of a Modified XELOX Regimen in First-Line Treatment of Metastatic Colorectal Adenocarcinoma

Inclusion Criteria: * Signed written informed consent; * Patients with histologically or cytologically confirmed stage IV colorectal adenocarcinoma whose ECOG performance status are 0-2; * Presence of measurable disease by radiographic study (including CT or MRI scan, or chest x-ray) or physical examination; * At least 3 weeks since last major surgery; * At least 12 months since last adjuvant chemotherapy; * At least 6 weeks since prior radiotherapy providing that the extent and site of radiotherapy fields are such that marked bone marrow suppression is NOT expected; * Patients who have received palliative radiotherapy must have recovered from any reversible toxic effects e.g. nausea and vomiting caused by radiation of fields; * Patients with reproductive potential must use effective BC; * Required Screening Laboratory Criteria: * Hemoglobin 90g/L * WBC 3.5 x 109/L * Neutrophils 1.5 x 109/L * Platelets 100 x 109/L * Creatinine 133 umol/L and creatinine clearance 60 mL/min * A probable life expectancy of at least 6 months; Exclusion Criteria: * Brain metastases; * Female of childbearing potential, pregnancy test is positive; * Concomitant malignancies or previous malignancies other than colorectal cancer within the last five years, with the exception of adequately treated basal or squamous cell carcinoma of the skin, carcinoma in situ of the cervix, or low grade prostate cancer; * Active infection; * Concurrent severe medical problems unrelated to the malignancy, which would significantly limit full compliance with the study or expose the patient to extreme risk; * Sexually active patients refusing to practice adequate contraception; * Patients with conditions which might affect absorption of an oral drug (for example intermittent obstruction) unless discussed and agreed with principal investigator; * History of grade 3 or 4 toxicity to fluoropyrimidines; * Pre-existing neuropathy ≥ NCI CTC grade 2.