Zinc, copper, copper-to-zinc ratio, and other biometals in blood serum and tumor tissue of patients with colorectal cancer

The objective of the present study was to assess serum and cancerous tissue biometal levels in colorectal cancer (CRC) patients, and its relation to disease severity. A total of 90 CRC patients and 97 controls were involved in the present study. The level of biometals in blood serum and colon tissues (only in CRC cases) was evaluated by inductively-coupled plasma mass-spectrometry. CRC patients are characterized by lower serum Ca, Fe, Se, and Zn, as well as higher serum Co, Cu, Mg, V, and Cu/Zn ratio compared to healthy controls. The lowest serum Zn levels and the highest Cu concentration and Cu/Zn ratio were observed in patients with the largest tumor size. Regression analysis demonstrated that tumor size is a significant negative predictor of serum Se levels, being positively associated with serum Cu/Zn values. The degree of metastasis to regional lymph nodes was inversely associated with circulating Ca, Co, Mg, Zn, and Mn levels. Serum Mg and Mn levels were positively associated with the stage of the disease and tumor location, respectively. Cancerous tissue Ca and Mo levels were lower, while Mg content was higher compared to healthy adjacent tissues. In cancerous tissues a constant but non-significant trend to elevation of tissue Zn content with increasing tumor size was observed. In addition, serum Cu, Zn, and Cu/Zn values positively correlated with the respective tumor values. These findings demonstrate that altered biometal metabolism is associated with CRC, while systemic Cu/Zn ratio may be indicative of Cu and Zn imbalance in cancerous tissue.