Biological-guided Metronomic Chemotherapy as Maintenance Strategy in Metastatic Colorectal Cancer

Before the start of induction therapy: Inclusion Criteria: * Histological proof of colorectal cancer (in case of a single metastasis, histological or cytological proof of this lesion should be obtained); * Distant metastases which are unresectable (patients with only local recurrence are not eligible); * Measurable disease (\> 1 cm on spiral CT scan or \> 2 cm on chest X-ray; liver ultrasound is not allowed). Serum CEA may not be used as a parameter for disease evaluation; Exclusion criteria * Prior adjuvant treatment for stage II/III colorectal cancer ending within 6 months before the start of induction treatment * Any prior adjuvant treatment after resection of distant metastases * Previous systemic treatment for advanced disease At randomisation: Inclusion criteria: * WHO performance status 0-1 (Karnofsky PS \> 70%); * Disease evaluation with proven SD, PR or CR according to RECIST after first-line induction treatment; * Laboratory values obtained ≤ 2 weeks prior to randomisation: adequate bone marrow function (Hb \> 6.0 mmol/L, absolute neutrophil count \> 1.5 x 109/L, platelets \> 100 x 109/L), renal function (serum creatinine ≤ 1.5x ULN and creatinine clearance, Cockroft formula, \> 30 ml/min), liver function (serum bilirubin ≤ 2 x ULN, serum transaminases ≤ 3 x ULN without presence of liver metastases or ≤ 5x ULN with presence of liver metastases); * Life expectancy \> 12 weeks; * Age: 18-75 years; * Negative pregnancy test in women with childbearing potential; * Expected adequacy of follow-up; * Institutional Review Board approval; * Written informed consent Exclusion criteria * Chronic active infection; * Any other concurrent severe or uncontrolled disease preventing the safe administration of study drugs;