CYP1B1 and breast cancer: Studies reporting the association between CYP1B1 polymorphisms and breast cancer have involved different populations but, have given rise to often inconsistent and/or contradicting findings even within the same ethnic groups.12–14,16–19 We undertook a case-control study of a genetically-uniform population of Han Chinese in the Ningxia Hui Autonomous Region of P. R. China in which genotype and allele frequency associations between CYP1B1 polymorphisms [in exon 2 (codon 119, G→T) and exon 3 (codon 432, G→C)] with breast cancer patients and healthy controls were determined.