The matrix metalloproteinases (MMPs) are a family of highly conserved metal-dependent proteolytic enzymes, their main function is to degrade different components of extracellular matrix (ECM). Moreover, they play roles in regulation of cell growth, apoptosis, angiogenesis and immune surveillance. Natural sequence variations in the MMP genes may result in differential expression of MMPs in different individuals and therefore may be associated,with the development and progression of diseases. The aim of this study is to assess the effects of the C-1562T polymorphism in the MMP-9 promoter on the risk of occurrence and lymphatic metastasis of non-small cell lung carcinoma (NSCLC). The MMP-9 genotyping was performed in 243 pathologically diagnosed NSCLC patients and 350 healthy controls without overt cancer by using polymerase chain reaction-restriction fragment length polymorphism analysis. The distribution of the MMP-9 genotypes in NSCLC patients and healthy controls was in consistent with Hardy-Weinberg equilibrium. The frequency of the C/C, C/T and T/T genotypes in healthy controls was 79.4, 20.6 and 0%, respectively. Neither the overall genotype nor alletotype distribution in NSCLC patients showed significant difference from that in healthy controls (P=0.21 and 0.43, respectively). Compared with the C/C genotype, genotypes with the T allele did not show significant influence on the risk of NSCLC development (age and gender adjusted OR=1.13, 95% CI=0.76-1.68). Stratification by onset age, smoking status and tumor histological type also showed no association between the MMP-9 polymorphism and the risk of NSCLC. Furthermore, the genotype distribution between NSCLC patients with and without lymphatic metastasis was not significantly different. Therefore, the present study suggests that the MMP-9 C-1562T polymorphism may not be used as a useful marker to predicate susceptibility and lymphatic metastasis in NSCLC. (C) 2005 Elsevier Ireland Ltd. All rights reserved.