Update analysis of studies on the MMP-9 -1562 C>T polymorphism and cancer risk

Polymorphisms in the matrix metalloproteinase (MMP) gene have been hypothesized to be functional and may contribute to genetic susceptibility to cancers. The common sequence variation in MMP-9 -1562 C>T (rs3918242), has been involved in cancer risk. However, results of the related published studies were somewhat controversial and underpowered in general. To clarify the role of MMP-9 -1562 C>T genotype in global cancer, we performed a meta-analysis of all the available published studies involving 4,124 cancer patients and 4,728 control subjects. The overall results indicated that there was no major association of the variant on cancer risk. However, stratified analysis by cancer type showed that the MMP-9 -1562 C>T polymorphism has a lower risk in colorectal cancer (OR = 0.80, 95%CI = 0.66-0.96, P (heterogeneity) = 0.391) and lung cancer (OR = 0.70, 95%CI = 0.51-0.96, P (heterogeneity) = 0.959) by allelic contrast. Furthermore, association of the MMP-9 -1562 C>T polymorphism and cancer risk was also observed in hospital-based studies under the dominant genetic model (OR = 0.87, 95%CI = 0.78-0.97, P (heterogeneity) = 0.355), allelic contrast (OR = 0.85, 95%CI = 0.75-0.96, P (heterogeneity) = 0.271) and heterozygote comparison (OR = 0.89, 95%CI = 0.79-0.99, P (heterogeneity) = 0.402). This pooled analysis showed evidence that the MMP-9 -1562 C>T polymorphism may decrease both the colorectal and lung cancer risk. Further prospective studies with larger numbers of participants worldwide are required to evaluate the association in more detail.