Epidemiologic assessment of the correlation between a particular variation in DNA sequence, or polymorphism, and risk for BC has been a dominant paradigm for many years. Thus far, these efforts have met with scant success [26]. A common limitation in design of such studies is that they involve assessment of a single polymorphism or occasionally, a few polymorphisms. Further, although the polymorphism assessed typically resides within a gene known to protect bronchial epithelium from carcinogens, oxidants, or DNA damage, the selection of the particular polymorphism for study is largely empiric, and not based on known functional properties. These are problems because multiple infrequent polymorphisms at different sites may all contribute to risk and unless the key polymorphisms can be identified through a functional test, a statistically valid assessment would require much larger study populations [27].