SFOLFOX/SFOLFIRI vs FOLFOX/FOLFIRI

Primary objectives: The first objective is to evaluate, in terms of Objective Response Rate (ORR), whether the combined infusional Leucovorin Sodium and 5-FU has the potential of being superior to the standard sequential administration of Leucovorin Calcium and 5-FU, both in combination with standard Irinotecan or Oxaliplatin. Primary endpoints: The primary end-point for efficacy is the Objective Response Rate (using RECIST criteria) during the treatment period.