CYP1B1 and breast cancer: Our results on CYP1B1 codon 119(G→T) confirm those of a study in a Japanese population.21 Nevertheless, we measured higher frequencies of the CYP1B1 codon 119(G→T) “T” allele among controls (0.16) and cases (0.29) in the Ningxia Han than were reported among controls (0.12) and cases (0.16) in the Japanese study.21 Therefore, CYP1B1 codon 119(G→T), which is thought to participate in the substrate recognition site 1 of CYP1B1 protein, is significantly associated with breast cancer in both the Ningxia Han (China) population and the Japanese.