Study on the association between smoking behavior and dopamine receptor D2 gene polymorphisms among lung cancer cases.

OBJECTIVE: To investigate the possible association between dopamine D2 receptor (DRD2) TaqI A and TaqI B genotypes as well as smoking behavior and the risk of lung cancer among Chinese Han people. METHODS: PCR was used to perform genotyping on peripheral WBC DNA from 326 lung cancer patients and 326 age, sex and ethnicity-matched healthy controls. Subjects were interviewed to obtain relevant information and lifetime history of tobacco use. RESULTS: There were no statistically significant differences in the distribution of DRD2 genotypes between lung cancer cases and controls. The DRD2 genotypes and smoking status showed no correlation among cases and among controls as well. However, among controls, the frequency of the DRD2 * A2/A2 genotype in smokers who smoked > or = 25 cigarettes/day appeared to be higher than that in those who smoked < 25 cigarettes/day (42.5% versus 26.1%, P = 0.047). A similar trend was also found for the DRD2 * B2/B2 genotype, which was linked to the DRD2 * A2/A2 genotype, although the difference was not significant (40.0% versus 26.1%, P = 0.091). In contrast to controls, no association was found between the DRD2 genotypes and smoking among lung cancer cases. CONCLUSION: Our results suggested that DRD2 * A2/A2 genotype might be associated with a greater smoking intensity in Chinese. Further studies are needed to confirm this preliminary finding.