MMP2 and malignant colon neoplasm: Analyses of polymorphisms rs1799750 in MMP-1, rs243865 in MMP-2, rs11568818 in MMP-7, rs2252070 in MMP-13 and rs28366003 in MT2A in relation to serum Zn level did not show significant association of tested SNPs with breast, lung and colon cancer risk among polish patients.