Clinical studies on iron kinetics. II. Iron-kinetics studies in patients with malignant neoplasms. With special references to ferrokinetics and 59Fe labeled iron-dextran studies.

Although extensive studies on the anemia and iron metabolism in patients with malignant neoplasms have been made, the pathogenesis of the anemia ob· served in cancer patients remains obscure. The first purpose of this paper is to elucidate the functional impairment in red cell production in patients with malignant neoplasm by means of ferrokinetic studies. The second one· is to clarify how the reticulo-endothelial cells partici· pate in alterations of iron metabolism in malignancy by means of 59Fe labeled iron-dextran. The third one is to enumerate sideroblasts in bone marrow smears of cancer patients for assessing stainable iron in erythroblasts. The results obtained were as follows: 1) Ferrokinetic studies with 59Fe-citrate showed the increased rate of erythropoiesis in patients with malignant neoplasm. However, studies on cases with infections gave results very similar to those in malignant neoplasms, suggesting the· existence of a mechanism common in both conditions. 2) The studies with 59 Fe labeled iron-dextran revealed a significant decrease of utilization of radioiron for hemoglobin synthesis from iron-dextran captured in reticulo-endothelial cells in malignant diseases. 3) The percentage of bone marrow sideroblasts in patients with malignant neoplasms showed a significant decrease with the mean value of 28 percent. The evidences obtained above demonstrated that the erythropoietic activity in patients with malignant neoplasms is maintained above normal, while there is an evident impairment of iron release from reticulo-endothelial cells. However, the mechanism responsible for the defect of iron release in malignancy is not clear and required further study.