Five groups of 587 inbred female mice (WHC) were studied to determine the incidence of tumors as affected by irradiation of different areas. A dose of 400 rad of 60Co was given to all the groups. One group of 166 mice was total body irradiated, another group of 90 mice was irradiated in the upper-third portion of the body, another group of 93 mice was irradiated in the lower two-thirds of the body, and another group of 90 mice was half body irradiated on the right side. As control, a group of 148 nonirradiated mice was followed. The results showed a different incidence of cancer in mice, depending not only on the irradiated areas but also on the shielded ones. This suggested that other factors besides irradiation affect carcinogenesis.
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 signficantly lower incidence of tumors in another two groups of mice that were immunized: in 80 nonirradiated vaccinated femal 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.
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