As part of this study, you will be asked to provide a saliva sample that will be collected at the first visit. To collect the saliva sample, you will be spitting into a container. Researchers will perform genetic tests with these samples to look for genes that control the production and use of neurotransmitters, naturally occurring chemical messengers in the brain. People with certain genes may have a more difficult time quitting smoking, because of the way nicotine affects these chemicals. The saliva sample will be stored in a biorepository at MD Anderson for use in future research related to nicotine addiction, smoking, and/or cancer.