Arterial chemotherapy in the management of colorectal cancer: an overview.

We have discussed the role of arterial therapy in patients with various stages and types of colon cancer. Arterial therapy is probably not useful as an adjuvant therapy for Dukes' C colon cancer. It may, however, play a role among patients with incomplete resection of liver metastases (positive margins). A randomized trial is needed to determine the role of arterial therapy in patients who have undergone complete resection of liver metastasis. Arterial therapy does not seem justified for patients with recurrent pelvic tumors. For nonresectable liver metastases, hepatic arterial therapy induces a higher response rate than does intravenous treatment. It may also improve performance status and offer additional palliation to patients who have failed systemic chemotherapy. are refractory to systemic chemotherapy may be candidates for palliative hepatic arterial chemotherapy even out of the context of a clinical trial. Asymptomatic patients with nonresectable liver metastasis who are refractory to systemic chemotherapy should be enrolled in phase I-II arterial chemotherapy trials designed to identify optimal treatment regimens. Previously untreated asymptomatic patients wishing treatment may be enrolled in a new multi-institutional phase III trial being designed to compare contemporary systemic chemotherapy with less toxic arterial therapy and combined arterial and systemic therapy. Such a new trial will have to avoid any cross-over between arms to determine the true impact of arterial therapy on survival. Regional arterial chemotherapy tries to extract the "extra mile" from marginally active drugs that have a steep dose response curve by increasing tumor drug exposure. Increased drug concentrations in the tumor may be accomplished by means of the blood vessel-to-tumor concentration gradient. The technology to achieve such a gradient has involved percutaneous hepatic arterial catheters, implantable infusion pumps or ports, and external pumps. The most economic hepatic arterial delivery system for protracted arterial FUdR is an infusion pump. Despite good pharmacological rationale, an improved response rate, and good evidence for effective palliation in advanced disease, hepatic arterial therapy has not improved survival when compared with systematic intravenous treatment. Possible explanations include the following: (1) poor study design that allowed patients to cross over between arms: (2) inadequate arterial chemotherapy combination; (3) inadequate arterial chemotherapy schedule; (4) hepatobiliary toxicity levels that required cessation of hepatic arterial therapy and allowed the emergence of resistant tumor clones; and (5) systemic progression of disease. Only time will tell whether improved chemotherapy and the design of a new phase III trial will establish a beneficial role for upfront hepatic arterial therapy in asymptomatic patients with colon cancer metastatic to the liver.