Leila Jouybari, Faezeh Kiani, Farhad Islami, Akram Sanagoo*, Fatemeh Sayehmiri, Bozena Hosnedlova, Monica Daniela Doşa, Rene Kizek, Salvatore Chirumbolo and Geir Bjørklund* Pages 1 - 10 ( 10 )
Breast cancer is the most common neoplasm, comprising 16% of all women's cancers worldwide. Research of copper (Cu) concentrations in various body specimens have suggested an association between Cu levels and breast cancer risks. This systematic review and meta-analysis summarize the results of published studies and examine this association. We searched the databases PubMed, Scopus, Web of Science, and Google Scholar and the reference lists of relevant publications. The standardized mean differences (SMD) between Cu levels in cancer cases and controls and corresponding confidence intervals (CI), as well as I² statistics, were calculated to examine heterogeneity.
Following the specimens used in the original studies, the Cu concentrations were examined in three subgroups: serum or plasma, breast tissue, and scalp hair. We identified 22 relevant studies published from 1984 to 2017. There was no statistically significant difference between breast cancer cases and controls for Cu levels assayed in any studied specimen; the SMD (95% CI) was -0.01 (-1.06 – 1.03; P = 0.98) for blood or serum, 0.51 (-0.70 – 1.73; P = 0.41) for breast tissue, and -0.88 (-3.42 – 1.65; P = 0.50) for hair samples. However, the heterogeneity between studies was very high (P < 0.001) in all subgroups. We did not find evidence for publication bias (P = 0.91). The results of this meta-analysis do not support an association between Cu levels and breast cancer. However, due to high heterogeneity in the results of original studies, this conclusion needs to be confirmed by well-designed prospective studies.
copper, breast cancer, women, blood, breast tissue, hair analysis
Nursing Research Center, Golestan University of Medical Sciences, Gorgan, Nursing Research Center, Golestan University of Medical Sciences, Gorgan, Surveillance and Health Services Research, American Cancer Society, Atlanta, Nursing Research Center, Golestan University of Medical Sciences, Gorgan, Student Research Committee, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Department of Human Pharmacology and Toxicology, Faculty of Pharmacy, University of Veterinary and Pharmaceutical Sciences Brno, Brno, Department of Pharmacology, Faculty of Medicine, Ovidius University, Constanta, Department of Human Pharmacology and Toxicology, Faculty of Pharmacy, University of Veterinary and Pharmaceutical Sciences Brno, Brno, Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Council for Nutritional and Environmental Medicine, Mo i Rana