Objective:To investigate the relationship between CYPIA1 genetic polymorphisms and the invasion and metastasis of breast cancer.Methods:The CYP1A1 gene polymorphism(an T-C transversion at nucleotide position 3801)was detected by the polymerase chain reaction and restriction fragment length polymorphism in 80 cases with breast cancer and 60 samples of normal breast tissue.The difference in genotypic distribution frequency between the groups,the correlation between the genotypes and the factors related to prognosis were analyzed.Results:The incidence of homozygous and variant genotypes had no difference between the breast cancer group and controls group(P=0.746).The proportion of variant genotype increased as clinical stage(P=0.006)advanced,as well as with increased numbers of lymph node metastases(P=0.010).Conclusions:In patients with breast cancer there is a correlation between the CYP1A1 CC allele and some factors indicating poor prognosis,including more lymph node metastases as well as a more advanced clinical stage. Objective: To investigate the relationship between CYPIA1 genetic polymorphisms and the invasion and metastasis of breast cancer. Methods: The CYP1A1 gene polymorphism (an TC transversion at nucleotide position 3801) was detected by the polymerase chain reaction and restriction fragment length polymorphism in 80 cases with breast cancer and 60 samples of normal breast tissue. The difference in genotypic distribution frequency between the groups, the correlation between the genotypes and the factors related to prognosis were analyzed. Results: The incidence of homozygous and variant genotypes had no difference between the breast cancer group and controls group (P = 0.746). The proportion of variant genotype increased as clinical stage (P = 0.006) advanced, as well as with increasing numbers of lymph node metastases (P = 0.010) .Conclusions: In patients with breast cancer there is a correlation between the CYP1A1 CC allele and some factors indicating poor prognosis, including more lymph node metastases as well as a more advanced clinical stage.