[Chemotherapy]

Cancer chemotherapy in the treatment of colorectal cancer has been evolving so extensively than ever. 5-fluorouracil (5-FU) has been a pivotal and a single active agent in the treatment of colorectal cancer. Reproducing and consistent better response rate has been shown since the introduction of the concept of biochemical modulation of 5-FU by leucovorin, a reduced folate, to the clinic and a combination chemotherapy of 5-FU and leucovorin (FL) has enable us to obtain a response rate around 20-30% and a median survival time ranging from 10 to 12 months. IFL regimen combing CPT-11 with FL showed a better MST ranging from 14 to 15 months, but now serious toxicity precludes general use outside of clinical trials. In the Europe, de Gramont regimen, an unique dose and schedule of 5-FU using a combination of continuous intravenous infusion of 5-FU with leucovorin over two days and bolus infusion of 5-FU twice over the same period, has been developed and shown improved antitumor activity and toxic profiles. FOLFOX 4, a combination chemotherapy of de Gramont regimen and oxaliplatin which is a third generation of cisplatin and a uniqe toxic profile with neuropathy, has demonstrated improved MST over a year and acceptable toxic profiles. Now FOLFOX 4 is considered to be a standard chemotherapy for the patients with advanced colorectal cancer, since a large phase III randomized study has shown that FOLFOX 4 was the most active and less toxic treatment regimen among active regimens such as IFL and IROX (CPT-11 and oxaliplatin). More recently, a combination of IFL and bevacizumab which is one of the molecular target agents and a antibody agent against vascular endothelial growth factor (VEGF), has demonstrated better MST reaching 20 months. Future large scale trials will attempt to develop more active regimen incorporating so-called molecular target agents.