The relationship between rs1051730, nicotine dependence, and lung cancer was more specifically explored by Spitz and colleagues.43 This was accomplished by using 3 samples: (1) patients with lung cancer and controls with a history of smoking, (2) patients with lung cancer and controls who were lifetime nonsmokers, and (3) patients with bladder cancer and controls with a history of smoking. The investigators found a statistically significant association of rs1051730 with lung cancer in subjects with a history of smoking. When stratified for number of cigarettes smoked per day, the highest risk was seen in the lightest smokers, subjects smoking less than 20 cigarettes per day. There was no association between lung cancer and rs1051730 in subjects who had never smoked and no association between rs1051730 and bladder and renal cancers. The investigators concluded that because the highest risk group was in the subjects who smoked the least, rs1051730 mediated risk to lung cancer beyond the cigarette exposure from nicotine dependence.
