Chemotherapy for Colorectal Cancer

ABSTRACT

Survival outcomes have been steadily improving for last 50 years in patients with colorectal cancer. The 5-fluorouracil (5-FU) is still one of the major chemotherapeutic agents. New cytotoxic agents, irinotecan and oxaliplatin, or targeted agents, bevacizumab and cetuximab, have been studied in the treatment of colon cancer. Adjuvant chemotherapy is indicated in patients with colon cancer at high-risk stage II and III, and after complete resection. Oxaliplatin-based regimens, FOLFOX, are considered as the standard adjuvant chemotherapy. If there are contraindications for oxaliplatin, the best alternatives are capecitabine or 5FU/LV. In rectal cancer, adjuvant chemotheradiotherapy is indicated in patients who had curative resection with stage II and III cancer. Adjuvant chemotherapy is necessary after neoadjuvant chemoradiotherapy in rectal cancer. The introduction of novel agents targeted to specific molecular features of cancer cells promises more options and marked improvements in efficacy for treatment of metastatic colon cancer. Bevacizumab has been shown to extend survival in colorectal cancer when used in combination with irinotecan and 5-fluorouracil-based chemotherapy, and the addition of cetuximab to irinotecan and 5-fluorouracil-based chemotherapy eliminates irinotecan resistance. Interestingly, there has been no clear association between the expression of epidermal growth factor receptor (EGFR) and response to the EGFR inhibitors. Instead, KRAS mutation has been accepted as a negative predictive factor for the treatment of cetuximab. In contrast, no valid biomarkers for bevacizimab were found so far. More studies are necessary to identify biomarkers of targeted agents. Recent advancement of chemotherapeutic agents extended survival in colorectal cancer.