The main findings of this study are the following: (1) The TIMP-2 gene rs4789936 polymorphism is associated with an increased risk of breast cancer in Southern Chinese women; (2) There are interactions between SNP rs4789936 polymorphism, smoking, drinking, and breast cancer risk; (3) The rs4789936 TT and CT genotypes are more frequent in breast cancer patients with lymph node metastases, advanced stage, and PR positive status; (4) The rs4789936 TT and CT genotypes are associated with a poor prognosis in breast cancer patients. This evidence concerns the gene TIMP2 and breast carcinoma.