Enhancement of Urethan Induction of Hepatomas in Mice by Prior Partial Hepatectomy

Summary

Urethan (25 mg dissolved in distilled water) was injected into strain C3H/HeA male mice 2 months of age. The mice were killed 13 months later. Eleven of thirty-six animals developed a hepatoma. Only 4% of the untreated males had developed a hepatoma at that age, which indicates that urethan accelerates hepatoma development if injected into adult mice. Two groups were partially hepatectomized at 2 months of age. Urethan was injected into the first group 7 days before the operation and into the second group, 4 days thereafter. In the first group, 18 of 36 mice developed one or more hepatomas (average 0.7/mouse), and in the second group, 16 of 19 (average 1.1/mouse). It is concluded that rapid liver proliferation following partial hepatectomy enhances urethan carcinogenesis in the mouse liver. In the three groups, a pulmonary tumor incidence of 83, 75, and 79% was found, the average number of tumors per mouse being 1.3, 1.7, and 1.6, respectively. Partial hepatectomy apparently does not influence the development of these lesions.