Sustained Enhanced Growth of Carcinoma EO771 in C57 Black Mice

Summary and Conclusions 1. Mammary carcinoma Eo771 was inoculated into 529 C-57 black mice in three series of experiments. Tumor growth in 109 control mice (12 experiments) injected with one Bar Harbor Eo771 mammary carcinoma strain averaged 2.7 cc at 19-20 days, and 41 control mice of the same strain (4 experiments) previously injected with heterologous XYZ material averaged 2.5 cc at 19-20 days. An additional 106 control mice in 11 experiments injected with a second Eo771 strain received from Bar Harbor about 1 year later averaged 2.5 cc at 20 days, indicating great uniformity in 2 different Bar Harbor strains of this tumor in Carworth Farms C57 black mice, there being no statistically significant differences. 2. In contrast, 129 C57 black mice in 13 experiments having a preliminary injection of Eo771 XYZ material 8-25 days before tumor transplantation had a 40%percnt; increased tumor volume at 19-20 days, or 3.6 cc. This difference of 0.99 ± 0.28 cc was statistically significant. 3. In an additional 17 experiments during the same period involving 144 mice of the same strain, mean tumor growth in 2-6 animal passages of tumor from an XYZ injected mouse averaged 5.3 cc or more than double the growth of Eo771 in control mice and some 40-50%percnt; greater than occurred in the first passage XYZ strains. Whether this greatly enhanced growth was a mutation or a variation induced by the XYZ treatment remains to be determined.