GSTM1, smoking and lung cancer : a case-control study

We conducted a case-control study to examine the risk of lung cancer in relation to GSTM1 polymorphism and cigarette smoking (primarily of black tobacco) in a French population. The 611 subjects were 301 incident lung cancer cases and 310 hospital controls. We were able to constitute a DNA bank for 547 subjects (89.5%) and gather detailed information on smoking history for all of them. Results presented here concern 247 cases and 254 controls. Taking non- or light smokers as the reference category, we estimated odds ratios (OR) of 4.2 (95% CI: 2.6-6.7) and 5.2 (95% CI: 3.3-8.3) for the medium and heavy smokers respectively. On the other hand we estimated that the crude OR associating GSTM1 with lung cancer was 1.3 (95% CI: 0.9-1.8). Furthermore our data do not depart significantly from a multiplicative model of the combined effects of smoking and GSTM1 deficiency. We conclude that smoking and the GSTM1 gene are each a risk factor for lung cancer, and that their combined effect does not differ significantly from that of a multiplicative model.