5-Fluorouracil plus leucovorin as adjuvant treatment of an experimental liver tumor in rats.

Recent experimental and clinical work has shown that leucovorin potentiates the cytotoxic effect of 5-fluorouracil (5-FU). To investigate the adjuvant role for this combination, 5-FU, 30 mg/kg, combined with leucovorin, 15 mg/kg, was administered intraperitoneally on 3 consecutive days beginning on the same day as tumor cell inoculation in the liver. Tumor take and tumor volume were registered on day 14, followed by recording of survival time. The results of the combined treatment were compared with treatment with 5-FU alone. Leucovorin in combination with 5-FU, but not 5-FU alone, significantly reduced the tumor take compared with untreated animals (p less than 0.01). The combination also resulted in smaller tumors compared with untreated animals (p less than 0.001) or with animals given 5-FU alone (p less than 0.01). The present study supports the use of leucovorin in combination with 5-FU as adjuvant treatment of patients with primary colorectal cancer.