The role of irinotecan and oxaliplatin in the treatment of advanced colorectal cancer.

Colorectal carcinoma is one of the most common malignancies in the western world, and although fluorouracil (5-FU) has been used in its treatment for almost 40 years, new agents with significant activity have been introduced recently. Irinotecan (CPT-11, Camptosar), a topoisomerase I inhibitor, administered at 300 to 350 mg/m2 every 3 weeks is significantly more active than continuous-infusion 5-FU in patients who have experienced disease progression after conventional therapy with 5-FU. In comparison to best supportive care, irinotecan improves survival and preserves quality of life despite treatment-related toxicity. Moreover, the combination of irinotecan and 5-FU has been explored in a number of different schedules. In previously untreated patients, overall response rates are high. Irinotecan can also be combined with mitomycin (mitomycin-C [Mutamycin]), oxaliplatin, or raltitrexed (Tomudex). Oxaliplatin is a new-generation platinum compound that has demonstrated activity against colorectal carcinoma in preclinical trials. It has been evaluated as a single agent against advanced colorectal carcinoma in the salvage setting and also in combination with 5-FU as initial therapy for metastatic disease (where it shows significant activity). The toxicity profile of oxaliplatin (chiefly characterized by neurotoxicity) differs from that of irinotecan (primarily producing diarrhea) and the potential, therefore, exists for combining these agents or for exploiting their possible synergy with 5-FU. The introduction of these two new active agents of different pharmacologic classes promises to enable significant improvements in the treatment of patients with colorectal carcinoma.