Influences of small doses of various corticosteroids on the incidence of chemically induced subcutaneous sarcomas in mice.

The influences of small doses of six important corticosteroids on the incidence of methylcholanthrene-induced subcutaneous sarcomas in Swiss mice have been studied. The incidence of subcutaneous methylcholanthrene-induced sarcomas in the dexamethasone-, triamcinolone-, methylprednisolone-, prednisolone-, and hydrocortisone-treated groups was depressed by once daily intraperitoneal injections of the corticosteroid in small doses. The ratio of the antineoplastic activity of these corticos teroids, i.e., the inhibitory activity on incidence of sarcoma, is almost the same as that of their anti-inflammatory activity. In the corticosteroid-treated groups, including the cortisone-treated animals, the occurrence of the first sarcoma was delayed for 1-3 weeks past the control group. The occurrence of the first fibrosarcoma was also delayed in all six corticosteroid-treated groups. As to the incidence of fibrosarcomas, it was reduced by administration of the corticosteroids in all the corticosteroid-treated groups, with the exception of the cortisone-treated group. However, the incidence of sarcomas and the percentage of fibrosarcomas in the cortisone-treated group were not lower than those in the control group. The reason for this must be that the dosage of cortisone was too small. It appears that the ratio of inhibitory effects of the corticosteroids to that of hydrocortisone on the incidence of sarcomas is not subject to the ratio of the anti-inflamma tory activities as measured by the cotton pellet implantation procedure but may be almost the same, as gauged by the croton oil granuloma-pouch test.