title: Association between four MMP-9 polymorphisms and breast cancer risk: a meta-analysis.
abstract: BACKGROUND
  The role of matrix metalloproteinase 9 (MMP-9) polymorphisms in breast cancer risk remains unclear. The purpose of this study was to evaluate the association between MMP-9 variants and breast cancer susceptibility.
  
  
  METHODS
  Case-control studies were searched on electronic databases to retrieve related articles published between 2000 and 2014 concerning the role of MMP-9 variants in breast cancer risk. Pooled odds ratios (OR) with correlative 95% confidence intervals (CI) were employed to assess this association.
  
  
  RESULTS
  Ten articles were screened out, including 6177 breast cancer patients and 6726 matched-controls. For rs3918242 (-1562 C/T), 6 studies contained 1435 patients and 1446 controls. Although the frequency of risk allele C was higher in breast cancer patients than in controls, only TT genotype in recessive model was significantly associated with increased risk of breast cancer (TT vs. CT+CC: OR=1.55, 95% CI=1.12-2.16, P=0.009) in a fixed-effects model. This significant relationship was not observed in other genetic models (P>0.05). No significant association was found between breast cancer risk and rs17576, rs2250889, and rs3787268 under any genetic models.
  
  
  CONCLUSIONS
  Our results show that TT genotype of MMP-9-1562 C/T polymorphism might be a risk factor for breast cancer. More studies are needed to further explore this association.
authors.affiliation: Life Science Research Center, Hebei North University, Zhangjiakou, Hebei, China (mainland).
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Zhang
authors.affiliation: College of Traditional Chinese Medicine, Hebei North University, Zhangjiakou, Hebei, China (mainland).
authors.forename: Guoyin
authors.initials: G
authors.lastname: Jin
authors.affiliation: Basic Medical College, Hebei North University, Zhangjiakou, Hebei, China (mainland).
authors.forename: Jianfeng
authors.initials: J
authors.lastname: Li
authors.affiliation: Life Science Research Center, Hebei North University, Zhangjiakou, Hebei, China (mainland).
authors.forename: Linxi
authors.initials: L
authors.lastname: Zhang
mesh_terms: D000483:Alleles; D001943:Breast Neoplasms / Q000201:enzymology* / Q000235:genetics*; D005260:Female; D005799:Genes, Dominant; D005808:Genes, Recessive; D056726:Genetic Association Studies; D020022:Genetic Predisposition to Disease; D006720:Homozygote; D006801:Humans; D020780:Matrix Metalloproteinase 9 / Q000235:genetics*; D008957:Models, Genetic; D020641:Polymorphism, Single Nucleotide / Q000235:genetics*; D017594:Publication Bias; D012307:Risk Factors
chemical_list: C579270:MMP9 protein, human; D020780:Matrix Metalloproteinase 9