Current treatment approaches in colorectal cancer

Fluorouracil (5-FU) is still the mainstay of adjuvant treatment for colorectal cancer. Two trials have shown a disease-free and overall survival benefit for 5-FU combined with levamisole in patients with node-positive colon cancer. This regimen is fairly well tolerated and devoid of long-term sequelae, and is now considered standard treatment for node-positive colon cancer. One trial showed a modest improvement in disease-free survival for the semustine/vincristine/5-FU combination; the leukemogenicity and renal toxicity caused by semustine have prevented this regimen from being adopted. Although administering 5-FU directly into the portal vein may improve disease-free survival, most trials have failed to demonstrate a reduction in the incidence of hepatic metastases. This technique, therefore, remains investigational. Several trials in rectal cancer show an advantage for 5-FU combined with semustine and radiation therapy in terms of disease-free survival, overall survival, or both; the contribution of semustine has been questioned and is currently being investigated. In patients with metastatic disease, hepatic arterial infusion of floxuridine produces a higher objective response rate than intravenous administration, but has not resulted in a survival benefit; hepatobiliary toxicity limits the duration of therapy. Biochemical modulation of 5-FU with leucovorin increases the response rate produced by 5-FU alone; a survival benefit has also been observed. N-(phosphonacetyl)-L-aspartate has shown initial promise in combination with high-dose 5-FU infusions. Among the many new drugs tested, only tauromustine seems worthy of further study.