Adjuvant therapy of colon cancer: current status and future directions

Adjuvant treatment of colon cancer is a relatively new concept, having been first validated less than 20 years ago. Fluoropyrimidines including 5-fluorouracil (5-FU), introduced in clinical trials in the 1950s, are an integral component of the treatment of colon cancer in the adjuvant setting. Whereas both irinotecan and oxaliplatin have demonstrated clinical activity in metastatic colorectal cancer, only oxaliplatin has demonstrated efficacy in the adjuvant setting when added to 5-FU-based therapy. Irinotecan, despite showing a survival advantage in the second-line metastatic cancer setting and a survival advantage when added to first-line metastatic cancer treatment, has failed to show a survival or disease-free survival benefit in the adjuvant setting. In contradistinction, the addition of oxaliplatin to 5-FU plus leucovorin has improved disease-free survival in 2 large randomized adjuvant trials. Oxaliplatin/5-FU/leucovorin should therefore be regarded as a reference standard for adjuvant therapy. This comprehensive review of adjuvant therapy for colon cancer will cover the role of fluoropyrimidines and oxaliplatin, the controversies of adjuvant therapy for patients with stage II cancer, and the ongoing clinical trials that will define the future role, or lack thereof, of newer agents in adjuvant therapy.