The significance of portal vein chemotherapy for liver micrometastases: an experimental study of a rat model.

To clarify the significance of prophylactic portal vein chemotherapy for hepatic metastases, the correlation between the timing of the portal infusion and the growth of liver micrometastases was examined in a rat model. Male Donryu rats weighing 160-180 g were first inoculated intraportally with 5 x 10(6) ascites hepatoma AH60C cells, following which an intraportal infusion of 5-fluorouracil (5-FU) 20 mg/kg/day with heparin 100 U/kg/day was given over 5 days, commencing on day 0, 3, and 6, in groups A, B, and C, respectively. Compared with a control group of rats which received no treatment, a significant inhibition of tumor growth and prolongation of survival time were observed in groups A (P < 0.01) and B (P < 0.05); however, group C, in which the mean diameter of the micrometastases was 0.52 +/- 0.10 mm at the commencement of the portal infusion, showed no therapeutic response. These results suggest that prophylactic portal vein chemotherapy should be given to prevent the lodgement of tumor cells in the portal system and inhibit their initial proliferation, rather than to destroy established micrometastases.