Treatment of colorectal cancer metastasis: the role of chemotherapy.

5-Fluorouracil (5-FU) has been the main chemotherapeutic agent for the treatment of colorectal cancer for four decades with modest efficacy. Modulation of 5-FU by leucovorin or continuous infusion improves the response rate, but overall survival duration remains approximately 12 months. Many oral fluoropyrimidines have been studied, including capecitabine, UFT, S-1, and Eniluracil. Capecitabine has demonstrated equivalent efficacy with 5-FU and has been approved as first line treatment. The combinations of capecitabine with CPT-11 or oxaliplatin are being developed. CPT-11 demonstrated non-crossover resistance with 5-FU and was proven to be effective treatment for patients who received prior 5-FU. CPT-11 in combination with 5-FU has demonstrated improved response rate and overall survival duration over 5-FU or CPT-11. Oxaliplatin plus 5-FU has offered another effective treatment option for colorectal cancer. Both 5-FU plus leucovorin in combination with CPT-11 or oxaliplatin are widely used first-line chemotherapies for advanced colorectal cancer. Optimal combinations and sequences of treatment are being studied, since several effective regimens have become available.