Serum and Tissue Zinc in Epithelial Malignancies: A Meta-Analysis

Abstract

Background and ObjectivesCurrent studies give us inconsistent results regarding the association of neoplasms and zinc(II) serum and tissues concentrations. The results of to-date studies using meta-analysis are summarized in this paper.MethodsWeb of Science (Science citation index expanded), PubMed (Medline), Embase and CENTRAL were searched. Articles were reviewed by two evaluators; quality was assessed by Newcastle-Ottawa scale; meta-analysis was performed including meta-regression and publication bias analysis.ResultsAnalysis was performed on 114 case control, cohort and cross-sectional studies of 22737 participants. Decreased serum zinc level was found in patients with lung (effect size = −1.04), head and neck (effect size = −1.43), breast (effect size = −0.93), liver (effect size = −2.29), stomach (effect size = −1.59), and prostate (effect size = −1.36) cancers; elevation was not proven in any tumor. More specific zinc patterns are evident at tissue level, showing increase in breast cancer tissue (effect size = 1.80) and decrease in prostatic (effect size = −3.90), liver (effect size = −8.26), lung (effect size = −3.12), and thyroid cancer (effect size = −2.84). The rest of the included tumors brought ambiguous results, both in serum and tissue zinc levels across the studies. The association between zinc level and stage or grade of tumor has not been revealed by meta-regression.ConclusionThis study provides evidence on cancer-specific tissue zinc level alteration. Although serum zinc decrease was associated with most tumors mentioned herein, further – prospective - studies are needed.

Status and Interrelationship of Zinc, Copper, Iron, Calcium and Selenium in Prostate Cancer

“…The potential reasons for a variable difference in tissue Zn level between PCa and BPH in studies may be-unwanted possible representative tissue sampling errors or ethnic related. Despite the evidence [29] for decrease in serum and tissue Zn as well as significance of zinc in PCa in experimental studies, the epidemiological data have shown mixed results between zinc status and PCa, varying from direct [30][31][32] to inverse [33][34][35] correlation and no significant correlation [7,36]. Higher levels of zinc supplementation have been shown to increase prostatic tissue zinc levels and induce intraepithelial carcinoma prostate in murine model [37].…”

Zinc Inhibits Hedgehog Autoprocessing

“…Decrease in zinc is observed early in the course of prostate cancer development, and the trend continues toward castration-resistant disease (40). Several studies showed the depression of zinc concentration in the cancerous human lung tissues, especially in the small cell lung cancer, the most malignant form in lung cancer (17,19,41). For ovarian cancer, serum zinc decreased in patients subsequently diagnosed with ovarian cancer, whereas in tumor tissue, the concentration of zinc also decreased (20,21).…”

The Quantitative Serum Brca1and Serum Zinc as a Novel Biomarkers With the Correlations Between Them in the Familial Breast Cancer Patients in Iraq.

“…[15] Many studies showed a correlation between low serum Zn levels and the risk for developing BC, others, revealed the erythrocytes Zn levels was significantly low in women with BC compared with normal women as it more correctly that didn't attributed to dietary Zn deficiency. [9] In the current study, almost patients had a Zinc supplement with their diet which declared in the questioner formula, however, serum zinc was significantly low that reflect a defective zinc metabolism in such patients, there was a high level of regulation of zinc importer (Zip) and transporter (ZnT) proteins families which enable the cellular zinc homeostasis (Chasapis CT, et al, 2014 Dec) [16] and several of these proteins appear to be disturbed in BC cells.…”

“…[9] In the current study, almost patients had a Zinc supplement with their diet which declared in the questioner formula, however, serum zinc was significantly low that reflect a defective zinc metabolism in such patients, there was a high level of regulation of zinc importer (Zip) and transporter (ZnT) proteins families which enable the cellular zinc homeostasis (Chasapis CT, et al, 2014 Dec) [16] and several of these proteins appear to be disturbed in BC cells. In Another complex issue was appeared when dealing with the regulation of serum Zn levels compared to its levels in the corresponding tumor tissues of cancer patients, breast biopsies from cancer patients have significantly higher Zn levels compared with normal breast tissues [9] , on the other hand, the majority of tumors, zinc level decrease in both serum and tissue to certain extent and it is uncertain, whether low serum level is a result of tumor, chronic stress or of both of these effects, that, leads to relocation of zinc between body compartments, in addition, chronic inflammation is a common mark of cancer which might be an important mechanism of serum zinc level decrease [15] , on the other hand, examination of BC biopsies as well as cultured cells revealed abnormal expression of multiple proteins that play a role in zinc homeostasis. [9] Moreover, abnormal functioning of both ZnTs and ZIPs as well as the imbalances in their activities could play a role in Zn dyshomeostasis and cancer development.…”