Prophylactic portal infusion chemotherapy as adjuvant therapy for the prevention of metachronous liver metastasis in colorectal cancer.

The DNA ploidy and DNA indices (DI) of 414 patients with colorectal cancer were analyzed, and the incidence of patients with metachronous liver metastasis was found to be significantly higher in those with aneuploid tumors and a DI above 1.5 than in those with aneuploid tumors and a DI below 1.4, or in those with diploid tumors and a DI equal to 1.0. Next, to confirm the effectiveness of administering prophylactic portal infusion chemotherapy (PPIC) as adjuvant therapy for the prevention of metachronous liver metastasis in colorectal cancer, a randomized controlled trial of PPIC was performed on 110 consecutive patients with primary colorectal cancer who had undergone curative resection. Although the incidence of patients with metachronous liver metastasis in the two study groups was not significantly different at 3.3% in the PPIC group and 10.3% in the control group, the incidence in the patients with aneuploidy and a DI above 1.5 was significantly lower in the PPIC group than in the control group. These findings suggest that colorectal cancer with aneuploidy and a DI above 1.5 may have a strong tendency to metastasize to the liver, and that prophylactic portal infusion chemotherapy may be effective for preventing metachronous liver metastasis in such patients.