Correlation of erythrocyte and plasma levels of zinc, copper, and iron with evidence of metastatic spread in cancer patients

The level of plasma copper (Cu‐PI) and zinc (Zn‐Pl) and the level of erythrocyte iron (Fe‐RBC), copper (Cu‐RBC), and zinc (Zn‐RBC) were determined in the blood of 70 normal donors and 138 patients with various solid tumors by diagnostic x‐ray spectrometry (DXS), a technique based on x‐ray fluorescence spectrometry analysis. There were no significant changes in the mean values of Zn‐Pl, Fe‐RBC, and Cu‐RBC in the patients when compared with those of normal donors. The mean level of Cu‐PI in the normal donors was 1.34 ± 0.37 μg/ml; it was significantly increased in the patients, ranging between 1.47 ± 0.34 μg/ml for patients without evidence of active cancer (NED) and 1.91 ± 0.76 μg/ml for patients with hepatic metastases. The most significant change observed was an increase in the Zn‐RBC found in the patients with clinical evidence of metastatic spread. Whereas the Zn‐RBC level in the normal donors was 9.85 ± 1.47 μg/g wet weight, and not significantly elevated in the NED patients, it was elevated to values of 11.37 ± 1.55 μg/g (P < 0.004) for patients with soft tissue and hepatic metastases and was 12.34 ± 1.65 μg/g (P < 0.001) for patients with bone metastases. The data suggest a clear correlation between Zn‐RBC and metastatic spread in nonlymphomatous human cancer.