Effect of uremia on tumor growth in mice

Outbred Swiss mice of the Hebrew University strain were subtotally nephrectomized. The experimental and control animals were both divided into two subgroups, with one group kept on a regular animal house diet and one on a low-protein diet. All the animals were injected with Ehrlich's ascites tumor cells s.c. into the neck region. Two weeks later, the animals were killed and the tumor was excised and weighed to the nearest milligram. Tumor size in the uremic animals--the nephrectomized animals kept on a regular diet--was significantly smaller than in all other groups, which had blood urea nitrogen levels well within the normal range. It is suggested that urea may be a factor responsible for inhibiting tumor growth.