No association between a single nucleotide polymorphism in CYP19 and breast cancer risk.

Introduction Genetic polymorphisms in CYP19 have been hypothesized to alter aromatase activity and have been examined in relationship with breast cancer risk (1–4). A greater frequency of tetranucleotide (TTTA)n repeat alleles in intron 4 have been reported among affected women (1,2). In a Scandinavian case-control study (cases/controls, 481/236) Kristensen et al. (4) observed a positive association between a SNP (C 3 T) in the untranslated region of exon 10 and risk of breast cancer (TT versus CC genotypes; OR, 2.00; 95% CI, 1.28–3.11), and a greater frequency of the TT genotype among women with larger and more advanced tumors. We assessed the association between CYP19 genotype, breast cancer risk, and endogenous steroid hormone levels in the prospective Nurses’ Health Study.