OBJECTIVETo investigate the relationship between polymorphisms of genes (CYP17, CYP19 and SULT1A1) involved in estrogen metabolism and susceptibility to breast cancer in Chinese women.

METHODSA case-control study was performed. PCR-base restriction fragment length polymorphism (PCR-RFLP) and short tandem repeat polymorphism (STRP) assays were used to detect the polymorphism distribution of CYP17, CYP19 and SULT1A1 in 213 breast cancer cases and 430 matched controls. Logistic regression analyses were used to determine the OR, multivariate adjusted OR and 95% CI of each and all three genes and estrogen exposure factors on the risk of breast cancer. Relationship between polymorphisms and clinic-pathological features was also assessed.

RESULTSThe frequency of A2 allele of CYP17 was 49.8% in cases and 49.1% in controls (P > 0.05). The frequency His allele of SULT1A1 in cases (13.6%) was significant higher than that of controls (9.5%) (P = 0.03). There was also significant difference in the frequencies of (TTTA)10 allele CYP19 which was 12.4% in cases and 8.2% in controls (P = 0.02). Multigenic model indicated that there was an increased risk of breast cancer with more numbers of high-risk genotypes in a dose-response effect (trend P = 0.05). Data from multivariate analysis showed that the allele of SULT1A1 His and CYP19 (TTTA)10 was positively associated with the risk of breast cancer. Other well-established risk factors as higher estrogen exposure including total years of menstrual, early menarche etc, and women with a higher BMI and WHR were all served as independent risks.

CONCLUSIONThis study indicated that the polymorphisms of estrogen-metabolizing genes were related to breast cancer.