To explicitly explore the potential contribution of altered nitrosamine pharmacology to lung cancer risk among smokers, we have extended our investigation of gene variants to CYP2B6. CYP2B6, like CYP2A6, is expressed in the lung in addition to the liver [4,5] and metabolically activates TSNAs to DNA-reactive products [2,6]. This evidence concerns the gene CYP2B6 and lung cancer.