Genetic variants in carcinogen-metabolizing enzymes, cigarette smoking and pancreatic cancer risk

Individual susceptibility to the toxic effects of cigarette smoke may be modified by inherited variability in carcinogen metabolism. The purpose of the present study was to investigate pancreatic cancer risk associated with cigarette smoking and 33 variants within carcinogen metabolism genes and examine whether these variants modify the association between smoking and pancreatic cancer. A population-based study was conducted with 455 pancreatic cancer cases and 893 controls. Epidemiological and smoking data were collected from questionnaires and variants were genotyped by mass spectrometry. Age- and sex-adjusted odds ratio (ASOR) and multivariate-adjusted odds ratio (MVOR) estimates were obtained using multivariate logistic regression, and interactions between each variant and smoking were investigated. Current smoker status [MVOR = 2.29, 95% confidence interval (95% CI): 1.62, 3.22], 10-27 pack-years (MVOR = 1.57, 95% CI: 1.13, 2.18), > 27 pack-years (MVOR = 1.77, 95% CI: 1.27, 2.46) and longer durations of smoking (19-32 years: MVOR = 1.46, 95% CI: 1.05, 2.05; > 32 years: MVOR = 1.78, 95% CI: 1.30, 2.45) were associated with increased pancreatic cancer risk. CYP1B1-4390-GG (ASOR = 0.36, 95% CI: 0.15, 0.86) and Uridine 5'-diphospho glucuronosyltransferase 1 family, polypeptide A7-622-CT (ASOR = 0.77, 95% CI: 0.60, 0.99) were associated with reduced risk. N-acetyltransferase 1-640-GT/GG (ASOR = 1.75, 95% CI: 1.00, 3.05), GSTM1 (rs737497)-GG (ASOR = 1.41, 95% CI: 1.02, 1.95), GSTM1 gene deletion (ASOR = 4.89, 95% CI: 3.52, 6.79) and glutathione S-transferase theta-1 gene deletion (ASOR = 4.41, 95% CI: 2.67, 7.29) were associated with increased risk. Significant interactions were observed between pack-years and EPHX1-415 (P = 0.04) and smoking status and N-acetyltransferase 2-857 (P = 0.03). Variants of carcinogen metabolism genes are independently associated with pancreatic cancer risk and may modify the risk posed by smoking.