Abstract
Summary
Mice of the T. M. strain were maintained from the age of 4 weeks on the Rockland rat diet (Group 1) supplemented with ether extract of whole powdered egg (Group 2), alcohol extract of egg yolk (Group 3) or with whole powdered egg from which the ether extractable part was removed (Group 4). The mice of the 4 groups were bred and their offspring maintained on the same diets. Each of the groups, consequently, consisted of mice of 5 to 6 generations. The results were: The mice of all 3 experimental groups developed a high incidence of malignancies, varying from 74.3% to 79.5%, as compared with the 15.9% of Group 1, the control. The incidence of the different malignancies was not the same in the mice on the diet supplemented with ether extract of whole egg as in those receiving alcohol extract of egg yolk or powdered egg from which the ether extractable part was removed. In the latter 2 groups the incidence of mammary cancer was considerably higher and that of the other types of malignancies (lung adeno carcinoma, lymphosarcomas, etc.) lower than in Group 2. This difference in incidence of the above two groups of malignancies is probably due to a difference in composition of the extracts used, since it is known that some lipids are more soluble in alcohol and others more in ether. In the case of Group 4, it is believed that the carcinogenicity is not due to the egg proteins, but to the unextracted lipids. These and other results indicate that there is more than one carcinogenic lipid in eggs.
Some slides were examined by Dr. Stephen S. Sternberg, Sloan-Kettering Inst., and some by Drs. Paul Kotin and Thelma B. Dunn, National Cancer Inst, to whom I am greatly indebted.
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