The present population-based case-control study of breast cancer in Germany evaluated the role of genetic polymorphisms in Phase I and II enzymes NAT1 and NAT2 in the AA pathway and CYP1A1, CYP1B1, GSTM1 and GSTT1 in the PAH pathway and cigarette smoke exposure in breast carcinogenesis. The gene discussed is NAT1; the disease is breast carcinoma.