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-Pl) 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-Pl in the normal donors was 1.34 +/- 0.37 micrograms/ml; it was significantly increased in the patients, ranging between 1.47 +/- 0.34 micrograms/ml for patients without evidence of active cancer (NED) and 1.91 +/- 0.76 micrograms/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 micrograms/g wet weight, and not significantly elevated in the NED patients, it was elevated to values of 11.37 +/- 1.55 micrograms/g (P less than 0.004) for patients with soft tissue and hepatic metastases and was 12.34 +/- 1.65 micrograms/g (P less than 0.001) for patients with bone metastases. The data suggest a clear correlation between Zn-RBC and metastatic spread in nonlymphomatous human cancer.