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.

MATERIAL AND 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.

Keywords: Breast Neoplasms - genetics, Alleles, Genes, Dominant, Genes, Recessive, Genetic Association Studies, Genetic Predisposition to Disease, Homozygote, Matrix Metalloproteinase 9 - genetics, Models, Genetic, Polymorphism, Single Nucleotide - genetics, Publication Bias, Risk Factors