Relationship between systemic 5-FU passage and response in colorectal cancer patients treated with intrahepatic...

The study described herein was conducted to analyze the relationship between tumor exposure to 5-FU and clinical response. Six patients were placed on continuous 5-day intrahepatic 5-FU chemotherapy for colorectal cancer metastasized to the liver. The starting dose was 600-800 mg/m2 per day; cycles were repeated at 4-week intervals. The 5-FU dose was increased by 250 mg/day at each cycle. All six patients received 3 or more cycles, for a total of 37 cycles. Response was evaluated after each cycle by ultrasonography or computed tomography (CT). Pharmacokinetic data revealed a high individual cycle-to-cycle variability for all six patients in the 5-FU area under the curve (AUC day 1 to day 5) corrected for the dose. These variations in drug biodisposition, reflecting hepatic 5-FU uptake, were significantly related to measurable modifications in the tumor mass in 71% of cycles. The correlation between the reduction in local drug exposure and tumor regrowth was better than that between the increase in local drug exposure and tumor reduction. These findings constitute an original illustration in humans of the experimental concept of the drug exposure/tumor response relationship for 5-FU.