A POLYMORPHISM IN THE CYP17 GENE INCREASES THE RISK OF BREAST-CANCER

We conducted a case-control study to determine whether a polymorphism in the CYP17 gene was associated with risk of breast cancer, We found an increased risk of advanced breast cancer in women carrying an A2 al lele. The odds ratio was 2.5 [95% confidence interval (CT), 1.07-5.94] for regional or metastatic disease, Among controls, the A1/A1 genotyp e was associated with a later age at menarche, The reduced risk of bre ast cancer associated with a later age of menarche was largely limited to A1/A1 women: odds ratio, 0.47 (CI, 0.22-0.98) for breast cancer an d later age at menarche among Al homozygotes compared with 0.80 (CI, 0 .51-1.27) for A1/A2 and A2/A2 genotypes. These findings suggest that t he CYP17 genotype may be a biomarker for the onset of ovulation and ad vanced breast cancer risk.