Tissue and Serum Trace Elements Concentration among Colorectal Patients: A Systematic Review of Case-Control Studies

BACKGROUND: Trace elements play a pivotal role in Colorectal Cancer (CRC) inhibition and development process. This systematic review provides the basic comparison of case-control studies focusing on concentration of trace elements between those with CRC and controls METHODS: The systematic review searched through two databases of Medline and Cochrane up to 24(th) June 2017. The search strategy focused on Population, Intervention, Comparison, and Outcomes (PICO). We searched the role of trace elements in cancer and focusing on case-control studies in CRC to obtain an insight into the differences in trace element concentrations between those with and without cancer. RESULTS: The serum concentrations of Ca, Cu, Mg, Mn, Se, Si, and Zn were lower in CRC patients but for Co and S the levels were higher in CRC patients. The concentrations of Cd, Cr, Cu, Mg, Mn, Pb, and Zn were increased in patients with metastasis, but not in Se. As for colon tissue specimens, inconsistent levels were reported between studies, notably in Cu, Se, and Zn. No changes were reported for B and Ca levels. Most of the trace elements in the tissue specimens showed higher concentrations of Cr, Fe, K, Mg, P, Rb, S, and Si compared to Br. CONCLUSION: With the growing interest to understand the link between trace elements in carcinogenesis and the possible interactions, multi assessment analysis of a larger cohort of samples is necessary.