Studies on the Anemia of Tumor-Bearing Animals. I. Distribution of Radioiron Following the Injection of Labeled Erythrocytes

Abstract

Iron distribution studies on rats bearing certain transplanted tumors indicated that the tumors contained large amounts of iron, frequently exceeding the total amount of iron found in the liver. Following the intravenous injection of Fe⁵⁹ labeled red cells into normal and tumor-bearing rats and mice, the Fe⁵⁹ concentration decreased at a more rapid rate in the tumor-bearing animals. The rate at which the Fe⁵⁹ concentration decreased, and the time after implantation of the tumor when the decrease started, varied markedly from tumor to tumor. The rate at which the Fe⁵⁹ left the blood of any single tumor-bearing animal varied randomly from day to day. The tumor-bearing animals frequently had larger blood volumes than those of their normal controls. In some instances the increased blood volume of the tumor-bearing animal was associated with an increased total body weight. In no instance did the change in blood volume more than partially account for the decrease in the concentration of labeled erythrocytes observed in the circulating blood of the tumor-bearing animals. A study of the distribution of Fe⁵⁹ in the normal and in the tumor-bearing animals revealed that a high proportion of the Fe⁵⁹ which had left the blood stream could be found in the area of the tumor. The loss of Fe⁵⁹ labeled erythrocytes from the blood stream was correlated with the amount of Fe⁵⁹ in the tumor, the onset of anemia, and the development of cachexia in the host.