MMP9 and colorectal cancer: The comparison of genotype and gene frequency distribution of MMP-2 gene−1306 (C/T), −790 (T/G), and MMP-9 gene R668Q and P574R between the colorectal cancer group and the control group (P > 0.05); MMP-2 gene−735 (C/T) locus CC genotype and MMP-9 gene−1562 (C/T) locus TT genotype are dangerous genotypes for colorectal cancer.