Copper and zinc concentrations in erythrocytes, plasma and whole blood were determined in mice bearing spontaneous-, transplanted- and benezo[a]pyrene-induced-tumour. The transplanted tumours studied were Sarcoma 180, Ehrlich carcinoma, and Dalton's lymphoma. Copper concentration in the malignant-tumour-bearing mice showed significant increases in erythrocytes and plasma, when compared with their normal controls. However, the zinc concentrations, although depressed in the different constituents of blood, were not significant enough to warrant any attention. Utilization of erythrocyte copper level as an additional marker of cancer activity is discussed.
