The present case-control study aimed to investigate the effect of polymorphisms in the genes CYP1A1, CYP1B1, COMT and CYP17, CYP19 and the BRCA1 founder mutation in relation to BC risk and to explore possible interactions between the gene polymorphisms and serum POP levels on BC risk in Greenlandic Inuit women. Here, CYP17A1 is linked to breast cancer.