[Anemia in malignant tumors. Loss of circulating transferrin due to lysosomal storage in human and rat malignant tumors].

The cellular uptake of 67Ga-labelled transferrin was studied in the carcinoma of the human respiratory tract and in the Morris hepatoma 5123 C of the rat. In both types of tumors a positive tumor imaging by 67Ga-transferrin scintigraphy was evident. The intracellular distribution pattern of the radioactivity showed that the incorporated 67Ga-transferrin is accumulated within the lysosomes of the tumors. The uptake of 67Ga-transferrin by the tumor cells resulted in a faster disappearance of the tracer from the blood. The accelerated disappearance of 67Ga-transferrin from the blood showed a direct correlation to the mass of tumor cells. The loss of circulating 67Ga-transferrin from the blood showed a close parallelism to the grade of the anemia observed in the tumor bearing rats. We conclude from these findings that the uptake of transferrin into the tumor cells is one of the factors which are responsible for the anemia observed in malignant diseases.