Active immunization against spontaneous tumors in mice

The incidence of spontaneous tumors was studied in a group of 136 female mice and in another group of 138 females after a sublethal dose of total body irradiation. Of the nonirradiated mice 10.2% developed mammary tumors, and 8% developed lung tumors. Of the irradiated mice 19.5% developed mammary tumors, 21.7% ovary tumors, 24.5% lung tumors, and 7.9% tumors in other organs. A vaccine was prepared for only mammary and ovary tumors through an original technique. The results showed a significantly lower incidence of tumors in another two groups of mice that were immunized: in 80 nonirradiated vaccinated female mice, mammary tumors decreased from 10.2% to 2.5%, and in 78 irradiated and vaccinated female mice, mammary tumors decreased from 19.5% to 8.9% and ovary tumors from 21.7% to 3.8%. Lung tumors also decreased in the latter group, suggesting a common factor protecting the immunized mice.