Evaluation of Serum Zinc Level Under Malignant Condition and its Possible Implication on Improving Cell-Mediated Immunity During Cancer Progression

Background Zinc is an essential trace element required for different biological functions in a living body. Evaluating its concentration and effect during malignancy is important not only to assess the disease activity but also to evaluate its role in some important biological activities like immunity. Methods The experiments were carried out in transplanted, chemically induced and spontaneous tumors in mice. The serum zinc concentration (SZC) was determined under malignant condition and following treatment of solid tumor with anti-cancer agents. The importance of evaluating Cu/Zn ratio (CZR) was also determined. To evaluate its role in immune response during malignancy, studies were carried out on induced tumor bearing animals. Results The results showed that SZC had an inverse correlation with the progression of the disease. It was significantly reduced in all forms of malignancy, more so in spontaneous and induced forms of the disease. Extensive studies done with the solid form of induced tumor, established the importance of estimating the concentration of Zn, in addition to that of copper, in assessing the disease activity following treatment with anti-cancer agents. With regression of the tumor mass, there was a significant elevation in the SZC and depression in the serum copper concentration (SCC) compared to their levels prior to treatment. This was also reflected on the value of copper zinc ratio (CZR); with the onset of tumor regression, a significant reduction in CZR was noted in the tumor bearing animals compared to their untreated levels. As the state of 'regression' in the tumor mass was maintained for a considerable period of time following treatment with anti-cancer agents along with elevated zinc levels, we considered the role of zinc in controlling the tumor growth, indirectly. We observed that zinc is able to stimulate lymphocyte proliferation that may directly impact on the immune response of tumor bearing host. Conclusions Zinc appears to play a role in tumor progression and regression and in stimulating lymphocyte proliferation. It is hypothesized that supplementing zinc to malignant subjects prior to and following therapeutic intervention with anti-cancer agents could help improve immune response of the host against existing tumor.