title: Glutathione S-transferase T1-null genotype interacts synergistically with heavy smoking on lung cancer risk.
abstract: We studied the influence of genotype for glutathione S-transferase T1 (GSTT1) on susceptibility to lung cancer among 184 Swedish lung cancer patients (88 never-smokers and 96 ever-smokers) and 162 matched population controls (79 never-smokers and 83 ever-smokers), with special emphasis on gene-environment interactions. Cases had significantly lower frequency of the GSTT1-null genotype than that of controls among never-smokers (4.6 vs. 16.5%, P = 0.02), whereas the frequencies were very close to each other among smokers (7.4 vs. 7.2%). Cases with high packyears of smoking, however, had a significantly higher frequency of the GSTT1-null genotype compared to that of cases with low packyears (18.3 vs. 5.6%, P = 0.005). Adjusted for age and gender, the GSTT1-null genotype appeared to be protective against lung cancer among never-smokers (odds ratio [OR] = 0.2, 95% confidence interval [CI] = 0.07-0.7), although it was associated with an increased risk for lung cancer among smokers (OR = 2.1, 95% CI = 0.8-5.9), mainly attributed to the group of heavy smokers (>23 packyears; OR = 3.5, 95% CI = 0.7-17.3). Heavy smoking conferred a threefold increased risk for lung cancer (OR = 2.6, 95% CI = 1.3-5.0) among GSTT1-positive individuals, but a ninefold increased risk when combined with the GSTT1-null genotype (OR = 9.3, 95% CI = 1.9-46.3, relative to GSTT1-positive light smokers). This joint effect was further demonstrated by a positive interaction between the GSTT1-null genotype and packyears of smoking. The risk of lung cancer increased steeply with increasing packyears among GSTT1-null smokers, whereas no such effect was seen among GSTT1-positive smokers. We conclude that the GSTT1-null genotype may strengthen the effect of heavy smoking on lung cancer risk.
authors.affiliation: Environmental Medicine Unit, Department of Biosciences, The Karolinska Institute, Center for Nutrition and Toxicology (CNT)/NOVUM, Huddinge, Sweden. saimei.hou@cnt.ki.se
authors.forename: S M
authors.initials: SM
authors.lastname: Hou
authors.forename: S
authors.initials: S
authors.lastname: Fält
authors.forename: F
authors.initials: F
authors.lastname: Nyberg
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D003043:Cocarcinogenesis; D005260:Female; D005838:Genotype; D005982:Glutathione Transferase / Q000235:genetics*; D006801:Humans; D008175:Lung Neoplasms / Q000201:enzymology / Q000209:etiology* / Q000235:genetics; D008297:Male; D008875:Middle Aged; D012907:Smoking / Q000009:adverse effects*
chemical_list: C413545:glutathione S-transferase T1; D005982:Glutathione Transferase