Smoking is the leading cause of preventable death, resulting in an estimated 438,000 premature deaths annually in the U.S. (1). Approximately 40% of these deaths are due to cancer, with lung cancer being the major contributor (1). Lung cancer risk increases with higher numbers of cigarettes smoked per day (2). Heavy smoking is also a strong predictor of nicotine dependence (3), which hampers the efforts by many of the 45.1 million smokers in the U.S. to quit smoking (4). Increased understanding of the genetic mechanisms underlying heavy smoking and nicotine dependence may aid in the development of drug therapies to help smokers quit.
