[Decreased plasma zinc levels in metastatic breast cancer]

Zinc is an essential component of many metalloenzymes for DNA and proteinsynthesis including RNA and DNA polymerases. It has been shown by several investigators that zinc is accumulated in breast cancer tissues. To investigate a possible relation between plasma zinc levels and tumor load, plasma zinc levels were evaluated in 76 patients with non metastatic breast cancer (no evidence for disease after mastectomy) and in 66 patients with metastatic breast cancer. Zinc concentrations were measured in plasma using an atomic absorption spectrophotometer (normal range 80-150 mcg/dl). In patients with metastatic disease plasma zinc concentrations were in the lower region of the normal range or depressed (arithmetic mean: 84.9 SD 21.6 mcg/dl), whereas patients with non metastatic breast cancer had normal zinc levels (arithmetic mean: 126.0 SD 27.7 mcg/dl). The difference between the two groups was highly significant (p = 0.001, t = -9.742, 140 degrees of freedom). It is concluded, that plasma zinc in breast cancer patients is depressed according to the stage of the disease. Based on experimental data a substitution of zinc cannot be recommended.